> ## Documentation Index
> Fetch the complete documentation index at: https://code.claude.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# Environment variables
> Reference for environment variables that control Claude Code behavior.
Environment variables can control Claude Code behavior such as model selection, authentication, request routing, and feature toggles. Many of the same behaviors can also be configured through a [settings file](/en/settings) field, a [CLI flag](/en/cli-reference), or an in-session command like `/model`.
This page covers how to:
* [Set environment variables](#set-environment-variables) in your shell or in a settings file
* [Check which value applies](#precedence) when a behavior can be set more than one way
* [Look up the variables Claude Code reads](#variables)
## Set environment variables
A variable you set in your shell lasts for that terminal session, while a variable in a settings file applies every time `claude` runs.
### In your shell
Set the variable before launching `claude`:
```bash theme={null}
export API_TIMEOUT_MS="1200000"
claude
```
To set it for every session, add the `export` line to `~/.bashrc`, `~/.zshrc`, or your shell's profile file.
```powershell theme={null}
$env:API_TIMEOUT_MS = "1200000"
claude
```
To set it for every session, run `[Environment]::SetEnvironmentVariable("API_TIMEOUT_MS", "1200000", "User")` and open a new terminal.
```batch theme={null}
set API_TIMEOUT_MS=1200000
claude
```
To set it for every session, run `setx API_TIMEOUT_MS "1200000"` and open a new terminal.
### In settings files
Add variables under the `env` key in a `settings.json` file. Claude Code reads them directly from the file at startup, so they take effect no matter how `claude` was launched.
```json ~/.claude/settings.json theme={null}
{
"env": {
"API_TIMEOUT_MS": "1200000",
"BASH_DEFAULT_TIMEOUT_MS": "300000"
}
}
```
The file you choose controls who the variables apply to:
| File | Applies to |
| :---------------------------- | :---------------------------------------------------------------------------- |
| `~/.claude/settings.json` | You, in every project |
| `.claude/settings.json` | Everyone working in the project, checked into source control |
| `.claude/settings.local.json` | You, in this project only (add it to your gitignore if you create it by hand) |
| Managed settings | Everyone in your organization, deployed by an admin |
See [Settings files](/en/settings#settings-files) for where each file lives and [Settings precedence](/en/settings#settings-precedence) for how they combine when more than one sets the same variable.
## Precedence
Where the same behavior has both an environment variable and a settings field, the environment variable takes precedence. For example, `ANTHROPIC_MODEL` overrides the `model` setting, and `CLAUDE_CODE_AUTO_CONNECT_IDE` overrides `autoConnectIde`. The settings field applies when the environment variable is not set.
How an environment variable interacts with CLI flags and in-session commands varies per feature: `--model` and `/model` override `ANTHROPIC_MODEL`, while `CLAUDE_CODE_EFFORT_LEVEL` overrides `/effort`. When a variable interacts with another configuration source, its row in the [Variables](#variables) list states the precedence or links to the page that documents it.
Claude Code reads environment variables at startup, so changes take effect the next time you launch `claude`.
## Variables
| Variable | Purpose |
| :------------------------------------------------------ | :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `ANTHROPIC_API_KEY` | API key sent as `X-Api-Key` header. When set, this key is used instead of your Claude Pro, Max, Team, or Enterprise subscription even if you are logged in. In non-interactive mode (`-p`), the key is always used when present. In interactive mode, you are prompted to approve the key once before it overrides your subscription. To use your subscription instead, run `unset ANTHROPIC_API_KEY` |
| `ANTHROPIC_AUTH_TOKEN` | Custom value for the `Authorization` header (the value you set here will be prefixed with `Bearer `) |
| `ANTHROPIC_AWS_API_KEY` | Workspace API key for [Claude Platform on AWS](/en/claude-platform-on-aws), generated in the AWS Console. Sent as `x-api-key` and takes precedence over AWS SigV4 |
| `ANTHROPIC_AWS_BASE_URL` | Override the [Claude Platform on AWS](/en/claude-platform-on-aws) endpoint URL. Use for custom regions or when routing through an [LLM gateway](/en/llm-gateway). Defaults to `https://aws-external-anthropic.{AWS_REGION}.api.aws` |
| `ANTHROPIC_AWS_WORKSPACE_ID` | Required for [Claude Platform on AWS](/en/claude-platform-on-aws). Sent on every request as the `anthropic-workspace-id` header |
| `ANTHROPIC_BASE_URL` | Override the API endpoint to route requests through a proxy or gateway. When set to a non-first-party host, [MCP tool search](/en/mcp#scale-with-mcp-tool-search) is disabled by default. Set `ENABLE_TOOL_SEARCH=true` if your proxy forwards `tool_reference` blocks. {/* min-version: 2.1.196 */}As of v2.1.196, [Remote Control](/en/remote-control#requirements) is disabled when this points at a host other than `api.anthropic.com`, matching its behavior on Amazon Bedrock, Google Cloud's Agent Platform, and Microsoft Foundry |
| `ANTHROPIC_BEDROCK_BASE_URL` | Override the Amazon Bedrock endpoint URL. Use for custom Amazon Bedrock endpoints or when routing through an [LLM gateway](/en/llm-gateway). See [Amazon Bedrock](/en/amazon-bedrock) |
| `ANTHROPIC_BEDROCK_MANTLE_BASE_URL` | Override the Amazon Bedrock Mantle endpoint URL. See [Mantle endpoint](/en/amazon-bedrock#use-the-mantle-endpoint) |
| `ANTHROPIC_BEDROCK_SERVICE_TIER` | Amazon Bedrock [service tier](https://docs.aws.amazon.com/bedrock/latest/userguide/service-tiers-inference.html) (`default`, `flex`, or `priority`). Sent as the `X-Amzn-Bedrock-Service-Tier` header. See [Amazon Bedrock](/en/amazon-bedrock#service-tiers) |
| `ANTHROPIC_BETAS` | Comma-separated list of additional `anthropic-beta` header values to include in API requests. Claude Code already sends the beta headers it needs; use this to opt into an [Anthropic API beta](https://platform.claude.com/docs/en/api/beta-headers) before Claude Code adds native support. Unlike the [`--betas` flag](/en/cli-reference#cli-flags), which requires API key authentication, this variable works with all auth methods including Claude.ai subscription |
| `ANTHROPIC_CUSTOM_HEADERS` | Custom headers to add to requests (`Name: Value` format, newline-separated for multiple headers) |
| `ANTHROPIC_CUSTOM_MODEL_OPTION` | Model ID to add as a custom entry in the `/model` picker. Use this to make a non-standard or gateway-specific model selectable without replacing built-in aliases. See [Model configuration](/en/model-config#add-a-custom-model-option) |
| `ANTHROPIC_CUSTOM_MODEL_OPTION_DESCRIPTION` | Display description for the custom model entry in the `/model` picker. Defaults to `Custom model ()` when not set |
| `ANTHROPIC_CUSTOM_MODEL_OPTION_NAME` | Display name for the custom model entry in the `/model` picker. Defaults to the model ID when not set |
| `ANTHROPIC_CUSTOM_MODEL_OPTION_SUPPORTED_CAPABILITIES` | See [Model configuration](/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_DEFAULT_FABLE_MODEL` | See [Model configuration](/en/model-config#environment-variables) |
| `ANTHROPIC_DEFAULT_FABLE_MODEL_DESCRIPTION` | See [Model configuration](/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_DEFAULT_FABLE_MODEL_NAME` | See [Model configuration](/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_DEFAULT_FABLE_MODEL_SUPPORTED_CAPABILITIES` | See [Model configuration](/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_DEFAULT_HAIKU_MODEL` | See [Model configuration](/en/model-config#environment-variables) |
| `ANTHROPIC_DEFAULT_HAIKU_MODEL_DESCRIPTION` | See [Model configuration](/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_DEFAULT_HAIKU_MODEL_NAME` | See [Model configuration](/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_DEFAULT_HAIKU_MODEL_SUPPORTED_CAPABILITIES` | See [Model configuration](/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_DEFAULT_OPUS_MODEL` | See [Model configuration](/en/model-config#environment-variables) |
| `ANTHROPIC_DEFAULT_OPUS_MODEL_DESCRIPTION` | See [Model configuration](/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_DEFAULT_OPUS_MODEL_NAME` | See [Model configuration](/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_DEFAULT_OPUS_MODEL_SUPPORTED_CAPABILITIES` | See [Model configuration](/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_DEFAULT_SONNET_MODEL` | See [Model configuration](/en/model-config#environment-variables) |
| `ANTHROPIC_DEFAULT_SONNET_MODEL_DESCRIPTION` | See [Model configuration](/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_DEFAULT_SONNET_MODEL_NAME` | See [Model configuration](/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_DEFAULT_SONNET_MODEL_SUPPORTED_CAPABILITIES` | See [Model configuration](/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_FOUNDRY_API_KEY` | API key for Microsoft Foundry authentication (see [Microsoft Foundry](/en/microsoft-foundry)) |
| `ANTHROPIC_FOUNDRY_AUTH_TOKEN` | {/* min-version: 2.1.203 */}Bearer token for Microsoft Foundry authentication, such as a Microsoft Entra access token. Claude Code sends it as the `Authorization: Bearer` header. Takes precedence over `ANTHROPIC_FOUNDRY_API_KEY` and over the Azure default credential chain. See [Microsoft Foundry](/en/microsoft-foundry). Requires Claude Code v2.1.203 or later |
| `ANTHROPIC_FOUNDRY_BASE_URL` | Full base URL for the Microsoft Foundry resource (for example, `https://my-resource.services.ai.azure.com/anthropic`). Alternative to `ANTHROPIC_FOUNDRY_RESOURCE` (see [Microsoft Foundry](/en/microsoft-foundry)) |
| `ANTHROPIC_FOUNDRY_RESOURCE` | Microsoft Foundry resource name (for example, `my-resource`). Required if `ANTHROPIC_FOUNDRY_BASE_URL` is not set (see [Microsoft Foundry](/en/microsoft-foundry)) |
| `ANTHROPIC_MODEL` | Name of the model setting to use (see [Model Configuration](/en/model-config#environment-variables)) |
| `ANTHROPIC_SMALL_FAST_MODEL` | \[DEPRECATED] Name of [Haiku-class model for background tasks](/en/costs) |
| `ANTHROPIC_SMALL_FAST_MODEL_AWS_REGION` | Override AWS region for the Haiku-class model when using Amazon Bedrock or Amazon Bedrock Mantle. On Amazon Bedrock, this only takes effect when `ANTHROPIC_DEFAULT_HAIKU_MODEL` or the deprecated `ANTHROPIC_SMALL_FAST_MODEL` is also set, since Amazon Bedrock otherwise uses the primary model for background tasks |
| `ANTHROPIC_VERTEX_BASE_URL` | Override Google Cloud's Agent Platform endpoint URL. Use for custom Google Cloud's Agent Platform endpoints or when routing through an [LLM gateway](/en/llm-gateway). See [Google Cloud's Agent Platform](/en/google-vertex-ai) |
| `ANTHROPIC_VERTEX_PROJECT_ID` | GCP project ID for Google Cloud's Agent Platform requests. Overridden by `GCLOUD_PROJECT`, `GOOGLE_CLOUD_PROJECT`, or the project in your `GOOGLE_APPLICATION_CREDENTIALS` credential file. See [Google Cloud's Agent Platform](/en/google-vertex-ai) |
| `ANTHROPIC_WORKSPACE_ID` | Workspace ID for [workload identity federation](https://platform.claude.com/docs/en/manage-claude/workload-identity-federation). Set this when your federation rule is scoped to more than one workspace so the token exchange knows which workspace to target |
| `API_FORCE_IDLE_TIMEOUT` | {/* min-version: 2.1.169 */}Override the 5-minute idle timeout that aborts a streaming model response when no bytes arrive. Set to `0` to disable the timeout, for example when a slow [gateway](/en/llm-gateway) or local model pauses longer than 5 minutes between chunks. Set to `1` to keep the timeout on every provider. When unset, the timeout is inactive on direct Anthropic API and [Claude Platform on AWS](/en/claude-platform-on-aws) connections, where Claude Code's own byte-level stream watchdog runs, and active on every other provider, including [Google Cloud's Agent Platform](/en/google-vertex-ai), [Microsoft Foundry](/en/microsoft-foundry), [Mantle](/en/amazon-bedrock#use-the-mantle-endpoint), [Amazon Bedrock](/en/amazon-bedrock), and gateway connections, so a stalled stream aborts instead of hanging. As of v2.1.169 |
| `API_TIMEOUT_MS` | Timeout for API requests in milliseconds (default: 600000, or 10 minutes; maximum: 2147483647). Increase this when requests time out on slow networks or when routing through a proxy. Values above the maximum overflow the underlying timer and cause requests to fail immediately |
| `AWS_BEARER_TOKEN_BEDROCK` | Amazon Bedrock API key for authentication (see [Amazon Bedrock API keys](https://aws.amazon.com/blogs/machine-learning/accelerate-ai-development-with-amazon-bedrock-api-keys/)) |
| `BASH_DEFAULT_TIMEOUT_MS` | Default timeout for long-running bash commands (default: 120000, or 2 minutes) |
| `BASH_MAX_OUTPUT_LENGTH` | Maximum number of characters in bash outputs before the full output is saved to a file and Claude receives the path plus a short preview. See [Bash tool behavior](/en/tools-reference#bash-tool-behavior) |
| `BASH_MAX_TIMEOUT_MS` | Maximum timeout the model can set for long-running bash commands (default: 600000, or 10 minutes) |
| `CCR_FORCE_BUNDLE` | Set to `1` to force [`claude --cloud`](/en/claude-code-on-the-web#send-local-repositories-without-github) to bundle and upload your local repository even when GitHub access is available |
| `CLAUDECODE` | Set to `1` in subprocesses Claude Code spawns (Bash and PowerShell tools, tmux sessions, [hook](/en/hooks) commands, [status line](/en/statusline) commands, stdio [MCP server](/en/mcp) subprocesses). IDE extensions also set this in their integrated terminals. Use to detect when a script is running inside a subprocess spawned by Claude Code. To check whether the current process was spawned directly by a tool call or hook, rather than inside a stdio MCP server that Claude Code started, use `CLAUDE_CODE_CHILD_SESSION` instead |
| `CLAUDE_AFK_COUNTDOWN_MS` | {/* min-version: 2.1.198 */}How many milliseconds before auto-continue the on-screen countdown appears on an unanswered [`AskUserQuestion`](/en/tools-reference) dialog. Default `20000` (20 seconds), capped at the auto-continue timeout. Has no effect unless auto-continue is on; see the [`askUserQuestionTimeout`](/en/settings#available-settings) setting and `CLAUDE_AFK_TIMEOUT_MS`. Requires Claude Code v2.1.198 or later |
| `CLAUDE_AFK_TIMEOUT_MS` | {/* min-version: 2.1.198 */}How many milliseconds of idle time before an unanswered [`AskUserQuestion`](/en/tools-reference) dialog auto-continues without you. {/* min-version: 2.1.200 */}Auto-continue is off by default; opt in with the [`askUserQuestionTimeout`](/en/settings#available-settings) setting. This variable is an override for demos and automated tests: when set, it takes precedence over that setting and turns auto-continue on even when the setting is unset or `never`. Setting `0` doesn't turn the timeout off; it closes the dialog immediately. In v2.1.198 and v2.1.199, auto-continue was on by default with a `60000` (60 seconds) timeout. Requires Claude Code v2.1.198 or later |
| `CLAUDE_AGENT_SDK_DISABLE_BUILTIN_AGENTS` | Set to `1` to disable all built-in [subagent](/en/sub-agents) types such as Explore and Plan. Only applies in non-interactive mode (the `-p` flag). Useful for SDK users who want a blank slate |
| `CLAUDE_AGENT_SDK_MCP_NO_PREFIX` | Set to `1` to skip the `mcp____` prefix on tool names from SDK-created MCP servers. Tools use their original names. SDK usage only |
| `CLAUDE_ASYNC_AGENT_STALL_TIMEOUT_MS` | Stall timeout in milliseconds for background subagents. Default `600000` (10 minutes). The timer resets on each streaming progress event; if no progress arrives within the window, the subagent is aborted and the task is marked failed, surfacing any partial result to the parent |
| `CLAUDE_AUTOCOMPACT_PCT_OVERRIDE` | Set the percentage (1-100) of the auto-compaction window at which auto-compaction triggers. Use lower values like `50` to compact earlier. This variable only causes earlier compaction when Claude Code compacts proactively: when `CLAUDE_CODE_AUTO_COMPACT_WINDOW` is set, in [cloud sessions](/en/claude-code-on-the-web), and on Sonnet 4.6 and Opus 4.6 without [extended context](/en/model-config#extended-context), which compact at the 200K boundary by default. On Sonnet 5, proactive compaction applies at the model's [default threshold](/en/model-config#sonnet-5-context-window). In other cases, such as a local session on Opus 4.8, auto-compaction triggers when the conversation reaches the model's context limit. The override can only lower the threshold, so values above the default have no effect. Applies to both main conversations and subagents |
| `CLAUDE_AUTO_BACKGROUND_TASKS` | Set to `1` to force-enable automatic backgrounding of long-running agent tasks. When enabled, subagents are moved to the background after running for approximately two minutes |
| `CLAUDE_AX_SCREEN_READER` | {/* min-version: 2.1.181 */}Set to `1` to render screen-reader friendly output: flat text without decorative borders or animations. Set to `0` to force screen-reader mode off even when [`axScreenReader`](/en/settings#available-settings) is `true`. The [`--ax-screen-reader`](/en/cli-reference#cli-flags) flag takes precedence. Requires Claude Code v2.1.181 or later |
| `CLAUDE_BASH_MAINTAIN_PROJECT_WORKING_DIR` | Return to the original working directory after each Bash or PowerShell command in the main session |
| `CLAUDE_CLIENT_PRESENCE_FILE` | {/* min-version: 2.1.181 */}Path to a file that an external tool, such as a screen-lock listener, creates when you unlock your screen and deletes when you lock it. While the file exists, Claude Code skips [Remote Control mobile push notifications](/en/remote-control#mobile-push-notifications), so you stop getting pushes while you are actively using the computer. When the file is absent or unreadable, notifications are sent as normal. Claude Code checks the file once per push-triggering event rather than polling it. Requires Claude Code v2.1.181 or later |
| `CLAUDE_CODE_ACCESSIBILITY` | Set to `1` to keep the native terminal cursor visible and disable the inverted-text cursor indicator. Allows screen magnifiers like macOS Zoom to track cursor position |
| `CLAUDE_CODE_ADDITIONAL_DIRECTORIES_CLAUDE_MD` | Set to `1` to load memory files from directories specified with `--add-dir`. Loads `CLAUDE.md`, `.claude/CLAUDE.md`, `.claude/rules/*.md`, and `CLAUDE.local.md`. By default, additional directories do not load memory files |
| `CLAUDE_CODE_ALT_SCREEN_FULL_REPAINT` | Set to `1` to repaint the entire screen on every frame in [fullscreen rendering](/en/fullscreen) instead of sending incremental updates. Use this if fullscreen mode shows stale or misplaced text fragments. Claude Code enables this automatically for background sessions and [agent view](/en/agent-view) on Windows |
| `CLAUDE_CODE_ALWAYS_ENABLE_EFFORT` | Set to `1` to send the [effort](/en/model-config#adjust-effort-level) parameter with every request, even when Claude Code does not recognize the model ID as effort-capable. Use this when routing through an [LLM gateway](/en/llm-gateway) or third-party provider that serves models under custom identifiers. Models that reject the effort parameter at the API, including Claude 3 models, Sonnet 4.0 and 4.5, Opus 4.0 and 4.1, and Haiku 4.5, are still excluded so requests do not fail |
| `CLAUDE_CODE_API_KEY_HELPER_TTL_MS` | Interval in milliseconds at which credentials should be refreshed (when using [`apiKeyHelper`](/en/settings#available-settings)) |
| `CLAUDE_CODE_ARTIFACT_AUTO_OPEN` | Set to `0` to stop Claude Code from opening the browser automatically when a new [artifact](/en/artifacts) is published. Republishing an existing artifact does not open the browser regardless of this setting |
| `CLAUDE_CODE_ATTRIBUTION_HEADER` | Set to `0` to omit the attribution block (client version and prompt fingerprint) from the start of the system prompt. Disabling it improves prompt-cache hit rates when routing through an [LLM gateway](/en/llm-gateway). Caching on a direct connection to the Anthropic API is unaffected either way |
| `CLAUDE_CODE_AUTO_COMPACT_WINDOW` | Set the context capacity in tokens used for auto-compaction calculations. Defaults to the model's context window, 200K for standard models or 1M for [extended context](/en/model-config#extended-context) models, except on Sonnet 5, which has its own [default threshold](/en/model-config#sonnet-5-context-window). Use a lower value like `500000` on a 1M model to treat the window as 500K for compaction purposes. The value is capped at the model's actual context window. `CLAUDE_AUTOCOMPACT_PCT_OVERRIDE` is applied as a percentage of this value. Setting this variable decouples the compaction threshold from the status line's `used_percentage`, which always uses the model's full context window |
| `CLAUDE_CODE_AUTO_CONNECT_IDE` | Override automatic [IDE connection](/en/vs-code). By default, Claude Code connects automatically when launched inside a supported IDE's integrated terminal. Set to `false` to prevent this. Set to `true` to force a connection attempt when auto-detection fails, such as when tmux obscures the parent terminal. Takes precedence over the [`autoConnectIde`](/en/settings#global-config-settings) global config setting |
| `CLAUDE_CODE_BRIDGE_SESSION_ID` | {/* min-version: 2.1.199 */}Set automatically in Bash tool and [hook command](/en/hooks) subprocesses while the session has an active [Remote Control](/en/remote-control) connection, and removed when the connection ends. The value is the session's ID in `session_` form, the same identifier that appears in the session's `claude.ai/code` URL, so a script can link back to the session that ran it. Requires Claude Code v2.1.199 or later. In [cloud sessions](/en/claude-code-on-the-web), read `CLAUDE_CODE_REMOTE_SESSION_ID` instead |
| `CLAUDE_CODE_CERT_STORE` | Comma-separated list of CA certificate sources for TLS connections. `bundled` is the Mozilla CA set shipped with Claude Code. `system` is the operating system trust store, read only on runtimes with `tls.getCACertificates`: the native binary, or Node 22.15 or later for npm installs. See [CA certificate store](/en/network-config#ca-certificate-store). Default is `bundled,system` |
| `CLAUDE_CODE_CHILD_SESSION` | {/* min-version: 2.1.172 */}Set to `1` in subprocesses Claude Code spawns via the Bash, PowerShell, and Monitor tools, [hook](/en/hooks) commands, and [status line](/en/statusline) commands. Not set for stdio [MCP server](/en/mcp) subprocesses, which are long-lived and outlive the session that spawned them. Unlike `CLAUDECODE`, this is only set by Claude Code itself when it launches a subprocess and not by IDE extensions, so it reliably distinguishes a nested session from a top-level `claude` launched in an IDE-integrated terminal. A nested interactive `claude` TUI started this way is automatically excluded from `--resume`, `--continue`, up-arrow history, and the `claude agents` list. Non-interactive `claude -p` sessions still persist. Set `CLAUDE_CODE_FORCE_SESSION_PERSISTENCE=1` to override this exclusion. Requires Claude Code v2.1.172 or later |
| `CLAUDE_CODE_CLIENT_CERT` | Path to client certificate file for mTLS authentication |
| `CLAUDE_CODE_CLIENT_KEY` | Path to client private key file for mTLS authentication |
| `CLAUDE_CODE_CLIENT_KEY_PASSPHRASE` | Passphrase for encrypted CLAUDE\_CODE\_CLIENT\_KEY (optional) |
| `CLAUDE_CODE_CONNECT_TIMEOUT_MS` | {/* max-version: 2.1.185 */}Removed in v2.1.186 and now a no-op. Previously set a separate timeout for the connect, TLS, and response-header phase of a streaming API request. Use `API_TIMEOUT_MS` for the per-request timeout |
| `CLAUDE_CODE_DEBUG_LOGS_DIR` | Override the debug log file path. Despite the name, this is a file path, not a directory. Requires debug mode to be enabled separately via `--debug`, `/debug`, or the `DEBUG` environment variable: setting this variable alone does not enable logging. The [`--debug-file`](/en/cli-reference#cli-flags) flag does both at once. Defaults to `~/.claude/debug/.txt` |
| `CLAUDE_CODE_DEBUG_LOG_LEVEL` | Minimum log level written to the debug log file. Values: `verbose`, `debug` (default), `info`, `warn`, `error`. Set to `verbose` to include high-volume diagnostics like full status line command output, or raise to `error` to reduce noise |
| `CLAUDE_CODE_DISABLE_1M_CONTEXT` | Set to `1` to disable [1M context window](/en/model-config#extended-context) support. When set, 1M model variants are unavailable in the model picker, and [Sonnet 5](/en/model-config#sonnet-5-context-window) sessions are treated as having a 200K window. Useful for enterprise environments with compliance requirements |
| `CLAUDE_CODE_DISABLE_ADAPTIVE_THINKING` | Set to `1` to disable [adaptive reasoning](/en/model-config#adjust-effort-level) on Opus 4.6 and Sonnet 4.6 and fall back to the fixed thinking budget controlled by `MAX_THINKING_TOKENS`. {/* min-version: 2.1.111 */}From v2.1.111, has no effect on Fable 5, Sonnet 5, or Opus 4.7 and later, which always use adaptive reasoning |
| `CLAUDE_CODE_DISABLE_ADVISOR_TOOL` | {/* min-version: 2.1.98 */}Set to `1` to disable the [advisor tool](/en/advisor). The `/advisor` command becomes unavailable, any configured `advisorModel` is ignored, and the `--advisor` flag is accepted but has no effect, so existing scripts that pass it continue to work without errors. Requires Claude Code v2.1.98 or later |
| `CLAUDE_CODE_DISABLE_AGENT_VIEW` | Set to `1` to turn off [background agents and agent view](/en/agent-view): `claude agents`, `--bg`, `/background`, and the on-demand supervisor. Equivalent to the [`disableAgentView`](/en/settings#available-settings) setting |
| `CLAUDE_CODE_DISABLE_ALTERNATE_SCREEN` | Set to `1` to disable [fullscreen rendering](/en/fullscreen) and use the classic main-screen renderer. The conversation stays in your terminal's native scrollback so `Cmd+f` and tmux copy mode work as usual. Takes precedence over `CLAUDE_CODE_NO_FLICKER` and the [`tui`](/en/settings#available-settings) setting. You can also switch with `/tui default`. Does not apply to background sessions opened from [agent view](/en/agent-view), which always use fullscreen rendering |
| `CLAUDE_CODE_DISABLE_ARTIFACT` | Set to `1` to disable the [Artifact](/en/artifacts) tool, which publishes session output as a private web page on claude.ai. Equivalent to the [`disableArtifact`](/en/settings#available-settings) setting |
| `CLAUDE_CODE_DISABLE_ATTACHMENTS` | Set to `1` to disable attachment processing. File mentions with `@` syntax are sent as plain text instead of being expanded into file content |
| `CLAUDE_CODE_DISABLE_AUTO_MEMORY` | Set to `1` to disable [auto memory](/en/memory#auto-memory). Set to `0` to force auto memory on even when `--bare` mode or [`autoMemoryEnabled: false`](/en/settings#available-settings) would otherwise disable it. When disabled, Claude does not create or load auto memory files |
| `CLAUDE_CODE_DISABLE_BACKGROUND_TASKS` | Set to `1` to disable all background task functionality, including the `run_in_background` parameter on Bash and subagent tools, auto-backgrounding, and the Ctrl+B shortcut |
| `CLAUDE_CODE_DISABLE_BG_EXIT_HANDOFF` | {/* min-version: 2.1.196 */}Set to `1` to stop a [background session's](/en/agent-view) running background shell commands, dynamic workflows, {/* min-version: 2.1.198 */}and, as of v2.1.198, background subagents when the [supervisor](/en/agent-view#the-supervisor-process) stops, restarts, or updates that session's process, instead of handing them to the session's next process. Affects only that handoff: backgrounding a session with `←` or [`/background`](/en/agent-view#from-inside-a-session) still carries in-flight work over, and `CLAUDE_DISABLE_ADOPT` turns off both. Requires Claude Code v2.1.196 or later |
| `CLAUDE_CODE_DISABLE_BG_SHELL_PRESSURE_REAP` | {/* min-version: 2.1.193 */}Set to `1` to stop Claude Code from terminating [background shell commands](/en/interactive-mode#background-bash-commands) when the operating system reports memory pressure. By default, on macOS and Linux, Claude Code terminates a background shell started in the main session on a memory-pressure signal once the session has been idle for 30 minutes and no turn or subagent is running. Windows has no memory-pressure signal, so this variable has no effect there. Requires Claude Code v2.1.193 or later |
| `CLAUDE_CODE_DISABLE_BUNDLED_SKILLS` | Set to `1` to disable the [skills](/en/skills) and workflows included with Claude Code: bundled skills and workflows are removed entirely, while built-in commands like `/init` stay typable but are hidden from the model. `/doctor` stays typable like the built-in commands; hide it with `DISABLE_DOCTOR_COMMAND` instead. Skills from plugins, `.claude/skills/`, and `.claude/commands/` are unaffected. Equivalent to the [`disableBundledSkills`](/en/settings#available-settings) setting; `0` doesn't override it |
| `CLAUDE_CODE_DISABLE_CLAUDE_MDS` | Set to `1` to prevent loading any CLAUDE.md memory files into context, including user, project, and auto-memory files |
| `CLAUDE_CODE_DISABLE_CRON` | Set to `1` to disable [scheduled tasks](/en/scheduled-tasks). The `/loop` skill and cron tools become unavailable and any already-scheduled tasks stop firing, including tasks that are already running mid-session |
| `CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS` | Set to `1` to strip Anthropic-specific `anthropic-beta` request headers and beta tool-schema fields (such as `defer_loading` and `eager_input_streaming`) from API requests. Use this when a proxy gateway rejects requests with errors like "Unexpected value(s) for the `anthropic-beta` header" or "Extra inputs are not permitted". Standard fields (`name`, `description`, `input_schema`, `cache_control`) are preserved |
| `CLAUDE_CODE_DISABLE_EXPLORE_PLAN_AGENTS` | {/* min-version: 2.1.198 */}Set to `1` to disable the built-in [Explore and Plan subagents](/en/sub-agents#built-in-subagents). Claude explores with its search tools or the general-purpose subagent instead, and [plan mode](/en/permission-modes#analyze-before-you-edit-with-plan-mode) reads files directly rather than launching Explore and Plan agents. Custom subagents named `Explore` or `Plan` are unaffected. To remove every built-in subagent type in the Agent SDK or non-interactive mode, use `CLAUDE_AGENT_SDK_DISABLE_BUILTIN_AGENTS` instead. Requires Claude Code v2.1.198 or later |
| `CLAUDE_CODE_DISABLE_FAST_MODE` | Set to `1` to disable [fast mode](/en/fast-mode) |
| `CLAUDE_CODE_DISABLE_FEEDBACK_SURVEY` | Set to `1` to disable the "How is Claude doing?" session quality surveys. Surveys are also disabled when `DISABLE_TELEMETRY`, `DO_NOT_TRACK`, or `CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC` is set, unless `CLAUDE_CODE_ENABLE_FEEDBACK_SURVEY_FOR_OTEL` opts back in. To set a sample rate instead of disabling outright, use the [`feedbackSurveyRate`](/en/settings#available-settings) setting. See [Session quality surveys](/en/data-usage#session-quality-surveys) |
| `CLAUDE_CODE_DISABLE_FILE_CHECKPOINTING` | Set to `1` to disable file [checkpointing](/en/checkpointing). The `/rewind` command will not be able to restore code changes |
| `CLAUDE_CODE_DISABLE_GIT_INSTRUCTIONS` | Set to `1` to remove built-in commit and PR workflow instructions and the git status snapshot from Claude's system prompt. Useful when using your own git workflow skills. Takes precedence over the [`includeGitInstructions`](/en/settings#available-settings) setting when set |
| `CLAUDE_CODE_DISABLE_LEGACY_MODEL_REMAP` | Set to `1` to prevent automatic remapping of Opus 4.0 and 4.1 to the current Opus version on the Anthropic API. Use when you intentionally want to pin an older model. The remap does not run on Amazon Bedrock, Google Cloud's Agent Platform, or Microsoft Foundry |
| `CLAUDE_CODE_DISABLE_MOUSE` | Set to `1` to disable mouse tracking in [fullscreen rendering](/en/fullscreen). Keyboard scrolling with `PgUp` and `PgDn` still works. Use this to keep your terminal's native copy-on-select behavior |
| `CLAUDE_CODE_DISABLE_MOUSE_CLICKS` | {/* min-version: 2.1.195 */}Set to `1` to disable click, drag, and hover handling in [fullscreen rendering](/en/fullscreen) while keeping mouse-wheel scrolling. Use this when you want wheel scroll to work inside Claude Code but don't want clicks to position the cursor, expand tool output, or open links. `CLAUDE_CODE_DISABLE_MOUSE` takes precedence when both are set. Requires Claude Code v2.1.195 or later |
| `CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC` | Equivalent of setting `DISABLE_AUTOUPDATER`, `DISABLE_FEEDBACK_COMMAND`, `DISABLE_ERROR_REPORTING`, and `DISABLE_TELEMETRY` |
| `CLAUDE_CODE_DISABLE_NONSTREAMING_FALLBACK` | Set to `1` to disable the non-streaming fallback when a streaming request fails mid-stream. Streaming errors propagate to the retry layer instead. Useful when a proxy or gateway causes the fallback to produce duplicate tool execution |
| `CLAUDE_CODE_DISABLE_NOTIFICATION_PRESENCE_CHECK` | {/* min-version: 2.1.193 */}Set to `1` to send the `PushNotification` tool's desktop notification even while you are typing in or focused on the terminal. By default the tool skips both the desktop notification and the [mobile push](/en/remote-control#mobile-push-notifications) when it detects recent keyboard activity or terminal focus. This variable disables only that local check, so the server can still suppress the mobile push when it detects that you are active. Requires Claude Code v2.1.193 or later |
| `CLAUDE_CODE_DISABLE_OFFICIAL_MARKETPLACE_AUTOINSTALL` | Set to `1` to skip automatic addition of the official plugin marketplace on first run |
| `CLAUDE_CODE_DISABLE_POLICY_SKILLS` | Set to `1` to skip loading skills from the system-wide managed skills directory. Useful for container or CI sessions that should not load operator-provisioned skills |
| `CLAUDE_CODE_DISABLE_TERMINAL_TITLE` | Set to `1` to disable automatic terminal title updates based on conversation context. In Agent SDK and `claude -p` sessions, this also skips the background Haiku request that generates the session title |
| `CLAUDE_CODE_DISABLE_THINKING` | Set to `1` to omit the `thinking` parameter from API requests entirely. This is a compatibility option for proxies and gateways that reject the parameter. The variable's behavior is unchanged from earlier versions; on models that think by default, omitting the parameter means the model may still think. To explicitly disable [extended thinking](https://platform.claude.com/docs/en/build-with-claude/extended-thinking) on the Anthropic API, use `MAX_THINKING_TOKENS=0` instead, which is also ineffective on Fable 5 since it cannot have thinking turned off. On [third-party providers](/en/third-party-integrations), `0` likewise omits the parameter, so the two variables behave the same there |
| `CLAUDE_CODE_DISABLE_VIRTUAL_SCROLL` | Set to `1` to disable virtual scrolling in [fullscreen rendering](/en/fullscreen) and render every message in the transcript. Use this if scrolling in fullscreen mode shows blank regions where messages should appear |
| `CLAUDE_CODE_DISABLE_WORKFLOWS` | Set to `1` to disable [workflows](/en/workflows#turn-workflows-off). Equivalent to the [`disableWorkflows`](/en/settings#available-settings) setting |
| `CLAUDE_CODE_EFFORT_LEVEL` | Set the effort level for supported models. Values: `low`, `medium`, `high`, `xhigh`, `max`, or `auto` to use the model default. Available levels depend on the model. Takes precedence over `/effort` and the `effortLevel` setting. See [Adjust effort level](/en/model-config#adjust-effort-level) |
| `CLAUDE_CODE_ENABLE_APPEND_SUBAGENT_PROMPT` | {/* min-version: 2.1.205 */}Set to `1` to enable appending extra text to the end of every [subagent](/en/sub-agents)'s system prompt. The [`--append-subagent-system-prompt`](/en/cli-reference#cli-flags) flag supplies the appended text and sets this variable automatically, so you don't need to set it yourself. Requires Claude Code v2.1.205 or later |
| `CLAUDE_CODE_ENABLE_AUTO_MODE` | {/* min-version: 2.1.158 */}Set to `1` to make [auto mode](/en/permission-modes#eliminate-prompts-with-auto-mode) available on Amazon Bedrock, Google Cloud's Agent Platform, Microsoft Foundry, and signed-in [Claude apps gateway](/en/claude-apps-gateway) sessions. Requires Claude Code v2.1.158 or later. Has no effect on the Anthropic API, where auto mode is available by default. See [Enable auto mode on Amazon Bedrock, Google Cloud's Agent Platform, or Microsoft Foundry](/en/permission-modes#enable-auto-mode-on-bedrock-agent-platform-or-foundry) |
| `CLAUDE_CODE_ENABLE_AWAY_SUMMARY` | Override [session recap](/en/interactive-mode#session-recap) availability. Set to `0` to force recaps off regardless of the `/config` toggle. Set to `1` to force recaps on when [`awaySummaryEnabled`](/en/settings#available-settings) is `false`. Takes precedence over the setting and `/config` toggle |
| `CLAUDE_CODE_ENABLE_BACKGROUND_PLUGIN_REFRESH` | Set to `1` to refresh plugin state at turn boundaries in [non-interactive mode](/en/headless) after a background install completes. Off by default because the refresh changes the system prompt mid-session, which invalidates [prompt caching](/en/prompt-caching) for that turn |
| `CLAUDE_CODE_ENABLE_FEEDBACK_SURVEY_FOR_OTEL` | Set to `1` to route the "How is Claude doing?" session quality survey to your own [OpenTelemetry collector](/en/monitoring-usage) when Anthropic-bound nonessential traffic is blocked. Survey ratings are emitted only as OTEL events to your configured collector. No survey data is sent to Anthropic in this mode. Applies when `CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC`, `DISABLE_TELEMETRY`, or `DO_NOT_TRACK` is set, and has no effect otherwise. `CLAUDE_CODE_DISABLE_FEEDBACK_SURVEY` and the organization product feedback policy take precedence |
| `CLAUDE_CODE_ENABLE_FINE_GRAINED_TOOL_STREAMING` | Controls whether tool call inputs stream from the API as Claude generates them. With this off, a large tool input such as a long file write arrives only after Claude finishes generating it, which can look like it's hanging. Enabled by default on the Anthropic API. On Amazon Bedrock and Google Cloud's Agent Platform, enabled per model where the deployed container supports it. Set to `0` to opt out. Set to `1` to force on when routing through a proxy via `ANTHROPIC_BASE_URL`, `ANTHROPIC_VERTEX_BASE_URL`, or `ANTHROPIC_BEDROCK_BASE_URL`. Off by default on Microsoft Foundry and [gateway](/en/llm-gateway) connections |
| `CLAUDE_CODE_ENABLE_GATEWAY_MODEL_DISCOVERY` | Set to `1` to populate the `/model` picker from your gateway's `/v1/models` endpoint when `ANTHROPIC_BASE_URL` points at an Anthropic-compatible gateway such as LiteLLM, Kong, or an internal proxy. Off by default because gateways backed by a shared API key would otherwise show every user every model the key can access. Discovered models are still filtered by an [`availableModels`](/en/settings#available-settings) allowlist the session receives; deliver the list through [MDM or a managed settings file](/en/settings#settings-files), since [server-managed delivery is not available on gateway configurations](/en/server-managed-settings#platform-availability) |
| `CLAUDE_CODE_ENABLE_OPUS_4_7_FAST_MODE` | {/* max-version: 2.1.141 */}Removed in v2.1.142, when the [fast mode](/en/fast-mode) default moved from Opus 4.6 to Opus 4.7 |
| `CLAUDE_CODE_ENABLE_PROMPT_SUGGESTION` | Set to `false` to disable prompt suggestions (the "Prompt suggestions" toggle in `/config`). These are the grayed-out predictions that appear in your prompt input after Claude responds. See [Prompt suggestions](/en/interactive-mode#prompt-suggestions) |
| `CLAUDE_CODE_ENABLE_TASKS` | Controls whether sessions use the structured Task tools (`TaskCreate`, `TaskUpdate`, `TaskGet`, `TaskList`) or the legacy `TodoWrite` tool. {/* min-version: 2.1.142 */}As of Claude Code v2.1.142, Task tools are the default in all modes. Set to `0` to revert to `TodoWrite`. See [Task list](/en/interactive-mode#task-list) and [Migrate to Task tools](/en/agent-sdk/todo-tracking#migrate-to-task-tools) |
| `CLAUDE_CODE_ENABLE_TELEMETRY` | Set to `1` to enable OpenTelemetry data collection for metrics and logging. Required before configuring OTel exporters. See [Monitoring](/en/monitoring-usage) |
| `CLAUDE_CODE_EXIT_AFTER_STOP_DELAY` | Time in milliseconds to wait after the query loop becomes idle before automatically exiting. Useful for automated workflows and scripts using SDK mode |
| `CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS` | Set to `1` to enable [agent teams](/en/agent-teams). Agent teams are experimental and disabled by default |
| `CLAUDE_CODE_EXTRA_BODY` | JSON object to merge into the top level of every API request body. Useful for passing provider-specific parameters that Claude Code does not expose directly |
| `CLAUDE_CODE_FILE_READ_MAX_OUTPUT_TOKENS` | Override the default token limit for file reads. Useful when you need to read larger files in full |
| `CLAUDE_CODE_FORCE_SESSION_PERSISTENCE` | {/* min-version: 2.1.172 */}Set to `1` to force transcript persistence, prompt history, and `claude agents` registration even when this `claude` was launched from inside another Claude Code session. Use when an inherited `CLAUDE_CODE_CHILD_SESSION` value, for example from a `screen` session or a background launcher first started by Claude Code's Bash tool, causes a genuine top-level session to be misclassified as nested. {/* min-version: 2.1.178 */}As of v2.1.178, Claude Code detects the tmux case automatically and ignores the inherited marker, so tmux no longer needs this variable. Also honored on v2.1.169 and earlier; has no effect on v2.1.170 and v2.1.171, where the nested-session detection it overrides was removed |
| `CLAUDE_CODE_FORCE_STRIKETHROUGH` | {/* min-version: 2.1.186 */}Set to `1` to force strikethrough rendering for `~~text~~` in Claude's responses when your terminal supports it but is not auto-detected, such as over SSH without `TERM_PROGRAM` forwarded. Without this, undetected terminals show the literal `~~` markers instead of rendering the text as strikethrough. Requires Claude Code v2.1.186 or later |
| `CLAUDE_CODE_FORCE_SYNC_OUTPUT` | Set to `1` to force-enable DEC private mode 2026 [synchronized output](https://gist.github.com/christianparpart/d8a62cc1ab659194337d73e399004036) when your terminal supports it but is not auto-detected. Useful for emulators such as Emacs `eat` that implement BSU/ESU but do not reply to the capability probe. Has no effect under tmux |
| `CLAUDE_CODE_FORK_SUBAGENT` | Set to `1` to let Claude spawn [forked subagents](/en/sub-agents#fork-the-current-conversation), or `0` to disable them, overriding any server-side rollout. When enabled, Claude can request the `fork` subagent type to spawn a fork, a subagent that inherits the full conversation context instead of starting fresh. Spawns without a subagent type still use the general-purpose subagent, and all subagent spawns run in the background. The explicit [`/fork`](/en/commands) command works without this variable. Works in interactive mode and via the SDK or `claude -p` |
| `CLAUDE_CODE_GIT_BASH_PATH` | Windows only: path to the Git Bash executable (`bash.exe`). Use when Git Bash is installed but not in your PATH. See [Windows setup](/en/setup#set-up-on-windows) |
| `CLAUDE_CODE_GLOB_HIDDEN` | Set to `false` to exclude dotfiles from results when Claude invokes the [Glob tool](/en/tools-reference#glob-tool-behavior). Included by default. Does not affect `@` file autocomplete, `ls`, Grep, or Read |
| `CLAUDE_CODE_GLOB_NO_IGNORE` | Set to `false` to make the [Glob tool](/en/tools-reference#glob-tool-behavior) respect `.gitignore` patterns. By default, Glob returns all matching files including gitignored ones. Does not affect `@` file autocomplete, which has its own [`respectGitignore` setting](/en/settings#available-settings) |
| `CLAUDE_CODE_GLOB_TIMEOUT_SECONDS` | Timeout in seconds for Glob tool file discovery. Defaults to 20 seconds on most platforms and 60 seconds on WSL |
| `CLAUDE_CODE_HIDE_CWD` | Set to `1` to hide the working directory in the startup logo. Useful for screenshares or recordings where the path exposes your OS username |
| `CLAUDE_CODE_IDE_HOST_OVERRIDE` | Override the host address used to connect to the IDE extension. By default Claude Code auto-detects the correct address, including WSL-to-Windows routing |
| `CLAUDE_CODE_IDE_SKIP_AUTO_INSTALL` | Set to `1` to skip auto-installation of IDE extensions. Equivalent to setting [`autoInstallIdeExtension`](/en/settings#global-config-settings) to `false` |
| `CLAUDE_CODE_IDE_SKIP_VALID_CHECK` | Set to `1` to skip validation of IDE lockfile entries during connection. Use when auto-connect fails to find your IDE despite it running |
| `CLAUDE_CODE_MAX_CONTEXT_TOKENS` | Override the context window size Claude Code assumes for the active model. {/* min-version: 2.1.193 */}As of v2.1.193, applied directly for model names Claude Code does not recognize as a Claude model; for recognized Claude models it only takes effect when `DISABLE_COMPACT` is also set. Use this when routing to a model through `ANTHROPIC_BASE_URL` whose context window does not match the built-in size for its name |
| `CLAUDE_CODE_MAX_OUTPUT_TOKENS` | Set the maximum number of output tokens for most requests. Defaults and caps vary by model; see [max output tokens](https://platform.claude.com/docs/en/about-claude/models/overview#latest-models-comparison). Increasing this value reduces the effective context window available before [auto-compaction](/en/costs#reduce-token-usage) triggers |
| `CLAUDE_CODE_MAX_RETRIES` | Override the number of times to retry failed API requests (default: 10). {/* min-version: 2.1.186 */}Capped at 15 as of v2.1.186; {/* min-version: 2.1.199 */}as of v2.1.199, `CLAUDE_CODE_RETRY_WATCHDOG` raises the default and removes the cap. For unattended sessions that need to wait through longer outages, set `CLAUDE_CODE_RETRY_WATCHDOG` instead |
| `CLAUDE_CODE_MAX_TOOL_USE_CONCURRENCY` | Maximum number of read-only tools and subagents that can execute in parallel (default: 10). Higher values increase parallelism but consume more resources |
| `CLAUDE_CODE_MAX_TURNS` | Cap the number of agentic turns when no explicit limit is passed. Equivalent to passing [`--max-turns`](/en/cli-reference#cli-flags), which takes precedence when both are set. A value that is not a positive integer is rejected at startup with an error rather than treated as no cap |
| `CLAUDE_CODE_MCP_ALLOWLIST_ENV` | Set to `1` to spawn stdio MCP servers with only a safe baseline environment plus the server's configured `env`, instead of inheriting your shell environment |
| `CLAUDE_CODE_MCP_TOOL_IDLE_TIMEOUT` | {/* min-version: 2.1.187 */}Idle timeout in milliseconds for MCP tool calls. When a stdio, HTTP, SSE, WebSocket, or [claude.ai connector](/en/mcp#use-mcp-servers-from-claude-ai) MCP server sends no response and no progress notification for this long, the tool call aborts with an error instead of waiting for the overall `MCP_TOOL_TIMEOUT`. Overrides the per-transport defaults of 300000 (5 minutes) for network servers and 1800000 (30 minutes) for stdio servers. Set to `0` to disable the idle check. Values below 1000 are raised to one second, and the value is capped at the effective `MCP_TOOL_TIMEOUT`. A per-server `timeout` in `.mcp.json` of at least 1000 raises that server's idle window to at least the `timeout` value. Doesn't apply to IDE servers or SDK in-process servers. Requires Claude Code v2.1.187 or later. {/* min-version: 2.1.203 */}Before v2.1.203, stdio servers were exempt from the idle timeout |
| `CLAUDE_CODE_NATIVE_CURSOR` | Set to `1` to show the terminal's own cursor at the input caret instead of a drawn block. The cursor respects the terminal's blink, shape, and focus settings |
| `CLAUDE_CODE_NEW_INIT` | Set to `1` to make `/init` run an interactive setup flow. The flow asks which files to generate, including CLAUDE.md, skills, and hooks, before exploring the codebase and writing them. Without this variable, `/init` generates a CLAUDE.md automatically without prompting |
| `CLAUDE_CODE_NO_FLICKER` | Set to `1` to enable [fullscreen rendering](/en/fullscreen), a research preview that reduces flicker and keeps memory flat in long conversations. Equivalent to the [`tui`](/en/settings#available-settings) setting; you can also switch with `/tui fullscreen` |
| `CLAUDE_CODE_OAUTH_REFRESH_TOKEN` | OAuth refresh token for Claude.ai authentication. When set, `claude auth login` exchanges this token directly instead of opening a browser. Requires `CLAUDE_CODE_OAUTH_SCOPES`. Useful for provisioning authentication in automated environments |
| `CLAUDE_CODE_OAUTH_SCOPES` | Space-separated OAuth scopes the refresh token was issued with, such as `"user:profile user:inference user:sessions:claude_code"`. Required when `CLAUDE_CODE_OAUTH_REFRESH_TOKEN` is set |
| `CLAUDE_CODE_OAUTH_TOKEN` | OAuth access token for Claude.ai authentication. Alternative to `/login` for SDK and automated environments. Takes precedence over keychain-stored credentials. Generate one with [`claude setup-token`](/en/authentication#generate-a-long-lived-token) |
| `CLAUDE_CODE_OPUS_4_6_FAST_MODE_OVERRIDE` | {/* max-version: 2.1.159 */}Removed in v2.1.160 and now a no-op. Previously pinned [fast mode](/en/fast-mode) to Claude Opus 4.6 instead of the current default. Opus 4.6 no longer supports fast mode |
| `CLAUDE_CODE_OTEL_DIAG_STDERR` | {/* min-version: 2.1.179 */}Set to `1` to write OpenTelemetry exporter diagnostic errors to stderr. By default these errors only appear with `--debug`, so a misconfigured exporter such as a Prometheus port collision otherwise fails silently. Requires Claude Code v2.1.179 or later. See [Monitoring](/en/monitoring-usage) |
| `CLAUDE_CODE_OTEL_FLUSH_TIMEOUT_MS` | Timeout in milliseconds for flushing pending OpenTelemetry spans (default: 5000). See [Monitoring](/en/monitoring-usage) |
| `CLAUDE_CODE_OTEL_HEADERS_HELPER_DEBOUNCE_MS` | Interval for refreshing dynamic OpenTelemetry headers in milliseconds (default: 1740000 / 29 minutes). See [Dynamic headers](/en/monitoring-usage#dynamic-headers) |
| `CLAUDE_CODE_OTEL_SHUTDOWN_TIMEOUT_MS` | Timeout in milliseconds for the OpenTelemetry exporter to finish on shutdown (default: 2000). Increase if metrics are dropped at exit. See [Monitoring](/en/monitoring-usage) |
| `CLAUDE_CODE_PACKAGE_MANAGER_AUTO_UPDATE` | Set to `1` to let Claude Code run your package manager's upgrade command in the background when a new version is available. Applies to Homebrew and WinGet installations. Other package managers continue to show the upgrade command without running it. See [Auto updates](/en/setup#auto-updates) |
| `CLAUDE_CODE_PERFORCE_MODE` | Set to `1` to enable Perforce-aware write protection. When set, Edit, Write, and NotebookEdit fail with a `p4 edit ` hint if the target file lacks the owner-write bit, which Perforce clears on synced files until `p4 edit` opens them. This prevents Claude Code from bypassing Perforce change tracking |
| `CLAUDE_CODE_PLUGIN_CACHE_DIR` | Override the plugins root directory. Despite the name, this sets the parent directory, not the cache itself: marketplaces and the plugin cache live in subdirectories under this path. Defaults to `~/.claude/plugins` |
| `CLAUDE_CODE_PLUGIN_GIT_TIMEOUT_MS` | Timeout in milliseconds for git operations when installing or updating plugins (default: 120000). Increase this value for large repositories or slow network connections. See [Git operations time out](/en/plugin-marketplaces#git-operations-time-out) |
| `CLAUDE_CODE_PLUGIN_KEEP_MARKETPLACE_ON_FAILURE` | Set to `1` to keep the existing marketplace cache when a `git pull` fails instead of wiping and re-cloning. Useful in offline or airgapped environments where re-cloning would fail the same way. See [Marketplace updates fail in offline environments](/en/plugin-marketplaces#marketplace-updates-fail-in-offline-environments) |
| `CLAUDE_CODE_PLUGIN_PREFER_HTTPS` | Set to `1` to clone GitHub `owner/repo` shorthand sources over HTTPS instead of SSH. Applies to plugin install and update, and to `/plugin marketplace add` and `update`. Useful in CI runners, containers, or any environment without a configured SSH key for `github.com` |
| `CLAUDE_CODE_PLUGIN_SEED_DIR` | Path to one or more read-only plugin seed directories, separated by `:` on Unix or `;` on Windows. Use this to bundle a pre-populated plugins directory into a container image. Claude Code registers marketplaces from these directories at startup and uses pre-cached plugins without re-cloning. See [Pre-populate plugins for containers](/en/plugin-marketplaces#pre-populate-plugins-for-containers) |
| `CLAUDE_CODE_POWERSHELL_RESPECT_EXECUTION_POLICY` | Set to `1` to stop Claude Code from passing `-ExecutionPolicy Bypass` when spawning PowerShell for tool calls, hooks, and status line commands, and respect the machine's effective execution policy instead. By default Claude Code bypasses execution policy at process scope so `.ps1` scripts and module imports work on default-Restricted Windows installs. Process-scope bypass never overrides Group Policy `MachinePolicy` or `UserPolicy` regardless of this setting |
| `CLAUDE_CODE_PRINT_BG_WAIT_CEILING_MS` | {/* min-version: 2.1.182 */}Maximum time in milliseconds that [non-interactive mode](/en/headless#background-tasks-at-exit) with the `-p` flag waits after the final turn for background subagents and workflows whose result is part of the output. Default: `600000`, or 10 minutes. When the cap is exceeded, remaining background tasks are terminated and the process exits. Set to `0` to wait indefinitely. This cap is separate from the five-second grace period that applies to plain background shells |
| `CLAUDE_CODE_PROPAGATE_TRACEPARENT` | {/* min-version: 2.1.152 */}Set to `1` to propagate W3C trace context when `ANTHROPIC_BASE_URL` points at a custom proxy. Propagation covers the `traceparent` header on model and HTTP MCP requests and the `TRACEPARENT` environment variable for Bash, PowerShell, and hook subprocesses. By default, propagation is enabled only when connected directly to the Anthropic API. Added in v2.1.152. See [Traces (beta)](/en/monitoring-usage#traces-beta) |
| `CLAUDE_CODE_PROVIDER_MANAGED_BY_HOST` | Set by host platforms that embed Claude Code and manage model provider routing on its behalf. When set, provider-selection, endpoint, and authentication variables such as `CLAUDE_CODE_USE_BEDROCK`, `ANTHROPIC_BASE_URL`, and `ANTHROPIC_API_KEY` in settings files are ignored so user settings cannot override the host's routing. The automatic telemetry opt-out for Amazon Bedrock, Google Cloud's Agent Platform, and Microsoft Foundry is also skipped, so telemetry follows the standard `DISABLE_TELEMETRY` opt-out. See [Default behaviors by API provider](/en/data-usage#default-behaviors-by-api-provider) |
| `CLAUDE_CODE_PROXY_RESOLVES_HOSTS` | Set to `1` to allow the proxy to perform DNS resolution instead of the caller. Opt-in for environments where the proxy should handle hostname resolution |
| `CLAUDE_CODE_REMOTE` | Set automatically to `true` when Claude Code is running as a [cloud session](/en/claude-code-on-the-web). Read this from a hook or setup script to detect whether you are in a cloud environment |
| `CLAUDE_CODE_REMOTE_SESSION_ID` | Set automatically in [cloud sessions](/en/claude-code-on-the-web) to the current session's ID. Read this to construct a link back to the session transcript. See [Link output back to the session](/en/claude-code-on-the-web#link-output-back-to-the-session) |
| `CLAUDE_CODE_RESUME_INTERRUPTED_TURN` | Set to `1` to automatically resume if the previous session ended mid-turn. Used in SDK mode so the model continues without requiring the SDK to re-send the prompt |
| `CLAUDE_CODE_RESUME_PROMPT` | Override the continuation message injected when resuming a session that ended mid-turn. Defaults to `Continue from where you left off.`. Spawn scripts for long-running agents can set this to a more directive boot message. An empty string uses the default |
| `CLAUDE_CODE_RETRY_WATCHDOG` | {/* min-version: 2.1.186 */}Set to `1` for unattended sessions such as eval harnesses, CI jobs, or remote workers. Retries `429` and `529` capacity errors indefinitely instead of failing after `CLAUDE_CODE_MAX_RETRIES` attempts. The watchdog backs off up to 5 minutes between attempts, or until the limit resets when the response carries a rate-limit reset time, so a session that hits a usage limit waits out the remaining window. {/* min-version: 2.1.199 */}As of v2.1.199 it also raises the default retry count for other transient errors, such as server errors, timeouts, and dropped connections, to 300, roughly three hours of backoff, and removes the cap of 15 on `CLAUDE_CODE_MAX_RETRIES` if you set that variable explicitly. Requires Claude Code v2.1.186 or later |
| `CLAUDE_CODE_SAFE_MODE` | Set to `1` to start in safe mode: CLAUDE.md, skills, plugins, hooks, MCP servers, custom commands and agents, output styles, workflows, custom themes, custom keybindings, status line and file-suggestion commands, LSP servers, and auto-memory do not load, for troubleshooting a broken configuration. Managed settings policy still applies, including policy-configured hooks, status line, and file-suggestion commands; managed plugins, managed skills, managed CLAUDE.md, and policy-configured MCP servers do not. Equivalent to passing [`--safe-mode`](/en/cli-reference#cli-flags). Directly spawned child processes inherit the variable |
| `CLAUDE_CODE_SCRIPT_CAPS` | JSON object limiting how many times specific scripts may be invoked per session when `CLAUDE_CODE_SUBPROCESS_ENV_SCRUB` is set. Keys are substrings matched against the command text; values are integer call limits. For example, `{"deploy.sh": 2}` allows `deploy.sh` to be called at most twice. Matching is substring-based so shell-expansion tricks like `./scripts/deploy.sh $(evil)` still count against the cap. Runtime fan-out via `xargs` or `find -exec` is not detected; this is a defense-in-depth control |
| `CLAUDE_CODE_SCROLL_SPEED` | Set the mouse wheel scroll multiplier in [fullscreen rendering](/en/fullscreen#mouse-wheel-scrolling). Accepts values from 1 to 20, and fractional values below 1 such as `0.5` to slow accelerated trackpad and wheel scrolling in terminals that already amplify wheel events. Set to `3` to match `vim` if your terminal sends one wheel event per notch without amplification. Ignored in the JetBrains IDE terminal, where Claude Code uses its own scroll handling |
| `CLAUDE_CODE_SESSIONEND_HOOKS_TIMEOUT_MS` | Override the time budget in milliseconds for [SessionEnd](/en/hooks#sessionend) hooks. Applies to session exit, `/clear`, and switching sessions via interactive `/resume`. By default the budget is 1.5 seconds, automatically raised to the highest per-hook `timeout` configured in settings files, up to 60 seconds. Timeouts on plugin-provided hooks do not raise the budget |
| `CLAUDE_CODE_SESSION_ID` | Set automatically to the current session ID in Bash and PowerShell tool subprocesses, [hook command](/en/hooks) subprocesses, and stdio [MCP server](/en/mcp) subprocesses. For Bash, PowerShell, and hooks this matches the `session_id` field in the hook JSON input and is updated on `/clear`. An MCP server subprocess retains the ID it was spawned with. On `--resume ` it receives the resumed ID, matching hooks and Bash. On `--continue` or `--resume` without an explicit ID it may receive the initial startup ID instead. Use to correlate scripts and external tools with the Claude Code session that launched them |
| `CLAUDE_CODE_SHELL` | Set the shell Claude Code uses to run Bash tool commands. Accepts a path to a `bash` or `zsh` binary, for example `/opt/homebrew/bin/bash`. Other shells such as `fish` are not supported. If the value is not a working `bash` or `zsh` path, Claude Code ignores it and falls back to auto-detection. Auto-detection uses your `$SHELL` when it points to `bash` or `zsh`, otherwise it picks the first working `zsh` then `bash` found on your `PATH` and standard install locations |
| `CLAUDE_CODE_SHELL_PREFIX` | Command prefix that wraps shell commands Claude Code spawns: Bash tool calls, [hook](/en/hooks) commands, [status line](/en/statusline) commands, and stdio [MCP server](/en/mcp) startup commands. PowerShell hooks and exec-form hooks run without the prefix. Useful for logging or auditing. Setting a bare executable path such as `/path/to/logger.sh` runs each command as `/path/to/logger.sh ''`. The wrapper receives the command line as a single shell-quoted argument in `$1`, so the wrapper must re-evaluate `$1` with a shell, for example `exec bash -c "$1"`. Treating `$1` as a bare executable path breaks stdio MCP servers that pass arguments such as `npx -y `. For Bash tool calls, `$1` contains the full shell invocation Claude Code assembles, including environment setup, not only the command Claude ran |
| `CLAUDE_CODE_SIMPLE` | Set to `1` to run with a minimal system prompt and only the Bash, file read, and file edit tools. MCP tools from `--mcp-config` are still available. Disables auto-discovery of hooks, skills, plugins, MCP servers, auto memory, and CLAUDE.md. OAuth tokens and keychain credentials are not read, so Anthropic authentication must come from `ANTHROPIC_API_KEY` or an `apiKeyHelper` in `--settings`. Equivalent to passing [`--bare`](/en/headless#start-faster-with-bare-mode) |
| `CLAUDE_CODE_SIMPLE_SYSTEM_PROMPT` | Set to `1` to use a shorter system prompt and abbreviated tool descriptions on any model. Set to `0`, `false`, `no`, or `off` to opt out even on models where the experiment or server configuration would otherwise enable it. The full tool set, hooks, MCP servers, and CLAUDE.md discovery remain enabled |
| `CLAUDE_CODE_SKIP_ANTHROPIC_AWS_AUTH` | Skip client-side authentication for [Claude Platform on AWS](/en/claude-platform-on-aws), for gateways that sign requests themselves |
| `CLAUDE_CODE_SKIP_BEDROCK_AUTH` | Skip AWS authentication for Amazon Bedrock (for example, when using an LLM gateway) |
| `CLAUDE_CODE_SKIP_FOUNDRY_AUTH` | Skip Azure authentication for Microsoft Foundry, for a proxy or gateway that injects its own `Authorization` header. Claude Code sends requests without an Azure credential and preserves the `Authorization` header you supply, for example through `ANTHROPIC_CUSTOM_HEADERS`. Ignored when `ANTHROPIC_FOUNDRY_API_KEY` or `ANTHROPIC_FOUNDRY_AUTH_TOKEN` is set. {/* min-version: 2.1.203 */}Before v2.1.203, this variable left the Microsoft Foundry client unable to send requests unless an API key was also set |
| `CLAUDE_CODE_SKIP_MANTLE_AUTH` | Skip AWS authentication for Amazon Bedrock Mantle (for example, when using an LLM gateway) |
| `CLAUDE_CODE_SKIP_PROMPT_HISTORY` | Set to `1` to skip writing prompt history and session transcripts to disk. Sessions started with this variable set do not appear in `--resume`, `--continue`, or up-arrow history. Useful for ephemeral scripted sessions |
| `CLAUDE_CODE_SKIP_VERTEX_AUTH` | Skip Google authentication for Google Cloud's Agent Platform (for example, when using an LLM gateway) |
| `CLAUDE_CODE_STOP_HOOK_BLOCK_CAP` | Maximum number of consecutive times a [Stop](/en/hooks#stop) or [SubagentStop](/en/hooks#subagentstop) hook may block the turn from ending before Claude Code overrides it and ends the turn anyway (default: 8). Set to `0` to disable the cap. Raise this if your hook legitimately needs more iterations to resolve |
| `CLAUDE_CODE_SUBAGENT_MODEL` | See [Model configuration](/en/model-config). {/* min-version: 2.1.196 */}As of v2.1.196, setting it to `inherit` is the same as leaving it unset; earlier versions treated `inherit` as an override that forced every subagent onto the main conversation's model |
| `CLAUDE_CODE_SUBPROCESS_ENV_SCRUB` | Set to `1` to strip Anthropic and cloud provider credentials from subprocess environments (Bash tool, hooks, MCP stdio servers). The parent Claude process keeps these credentials for API calls, but child processes cannot read them, reducing exposure to prompt injection attacks that attempt to exfiltrate secrets via shell expansion. On Linux, this also runs Bash subprocesses in an isolated PID namespace so they cannot read host process environments via `/proc`; as a side effect, `ps`, `pgrep`, and `kill` cannot see or signal host processes. `claude-code-action` sets this automatically when `allowed_non_write_users` is configured |
| `CLAUDE_CODE_SYNC_PLUGIN_INSTALL` | Set to `1` in non-interactive mode (the `-p` flag) to wait for plugin installation to complete before the first query. Without this, plugins install in the background and may not be available on the first turn. Combine with `CLAUDE_CODE_SYNC_PLUGIN_INSTALL_TIMEOUT_MS` to bound the wait |
| `CLAUDE_CODE_SYNC_PLUGIN_INSTALL_TIMEOUT_MS` | Timeout in milliseconds for synchronous plugin installation. When exceeded, Claude Code proceeds without plugins and logs an error. No default: without this variable, synchronous installation waits until complete |
| `CLAUDE_CODE_SYNC_SKILLS` | Set to `1` to download your enabled claude.ai skills into `~/.claude/skills/` before the first query and resync every 10 minutes. Applies only in non-interactive mode with the `-p` flag. Requires claude.ai authentication. [Claude Code on the web](/en/claude-code-on-the-web) sessions receive your enabled claude.ai skills automatically; you don't need to set this there |
| `CLAUDE_CODE_SYNC_SKILLS_INSTALL_TIMEOUT_MS` | Timeout in milliseconds for a mid-session skills resync when `CLAUDE_CODE_SYNC_SKILLS` is set (default: 30000). Bounds the download triggered when the host requests a skill reload during the session. When exceeded, the resync stops and remaining downloads continue in the background |
| `CLAUDE_CODE_SYNC_SKILLS_WAIT_TIMEOUT_MS` | Timeout in milliseconds for the first query to wait on the initial skills sync when `CLAUDE_CODE_SYNC_SKILLS` is set (default: 5000). When exceeded, the query proceeds and remaining skill downloads continue in the background |
| `CLAUDE_CODE_SYNTAX_HIGHLIGHT` | Set to `false` to disable syntax highlighting in diff output. Useful when colors interfere with your terminal setup. To also disable highlighting in code blocks and file previews, use the [`syntaxHighlightingDisabled`](/en/settings) setting |
| `CLAUDE_CODE_TASK_LIST_ID` | Share a task list across sessions. Set the same ID in multiple Claude Code instances to coordinate on a shared task list. See [Task list](/en/interactive-mode#task-list) |
| `CLAUDE_CODE_TEAM_NAME` | Name of the agent team this teammate belongs to. Set automatically on [agent team](/en/agent-teams) members |
| `CLAUDE_CODE_TMPDIR` | Override the temp directory used for internal temp files. Claude Code appends `/claude-{uid}/` on Unix or `/claude/` on Windows to this path. Default: `/tmp` on macOS, `os.tmpdir()` on Linux and Windows. {/* min-version: 2.1.161 */}As of v2.1.161, on macOS and Linux, [sandboxed](/en/sandboxing) Bash subprocesses receive a short fallback `$TMPDIR` under the system default when your override is a long path, since some tools fail when temp paths get too long. Unsandboxed Bash commands inherit your shell's `$TMPDIR` unchanged. Claude Code's own temp files always use your override |
| `CLAUDE_CODE_TMUX_TRUECOLOR` | Set to `1` to allow 24-bit truecolor output inside tmux. By default, Claude Code clamps to 256 colors when `$TMUX` is set because tmux does not pass through truecolor escape sequences unless configured to. Set this after adding `set -ga terminal-overrides ',*:Tc'` to your `~/.tmux.conf`. See [Terminal configuration](/en/terminal-config) for other tmux settings |
| `CLAUDE_CODE_USE_ANTHROPIC_AWS` | Use [Claude Platform on AWS](/en/claude-platform-on-aws) |
| `CLAUDE_CODE_USE_BEDROCK` | Use [Amazon Bedrock](/en/amazon-bedrock) |
| `CLAUDE_CODE_USE_FOUNDRY` | Use [Microsoft Foundry](/en/microsoft-foundry) |
| `CLAUDE_CODE_USE_MANTLE` | Use the Amazon Bedrock [Mantle endpoint](/en/amazon-bedrock#use-the-mantle-endpoint) |
| `CLAUDE_CODE_USE_NATIVE_FILE_SEARCH` | Set to `1` to discover custom commands, subagents, and output styles using Node.js file APIs instead of ripgrep. Set this if the bundled ripgrep binary is unavailable or blocked in your environment. Does not affect the Grep or file search tools |
| `CLAUDE_CODE_USE_POWERSHELL_TOOL` | Controls the PowerShell tool. On Windows without Git Bash, the tool is enabled automatically; set to `0` to disable it. On Windows with Git Bash installed, the tool is rolling out progressively: set to `1` to opt in or `0` to opt out. On Linux, macOS, and WSL, set to `1` to enable it, which requires `pwsh` on your `PATH`. When enabled on Windows, Claude can run PowerShell commands natively instead of routing through Git Bash. See [PowerShell tool](/en/tools-reference#powershell-tool) |
| `CLAUDE_CODE_USE_VERTEX` | Use [Google Cloud's Agent Platform](/en/google-vertex-ai) |
| `CLAUDE_CONFIG_DIR` | Override the configuration directory (default: `~/.claude`). All settings, session history, and plugins are stored under this path, as are credentials on Linux and Windows; on macOS, credentials are in the system Keychain. Useful for running multiple accounts side by side: for example, `alias claude-work='CLAUDE_CONFIG_DIR=~/.claude-work claude'` |
| `CLAUDE_DISABLE_ADOPT` | {/* min-version: 2.1.195 */}Set to `1` to stop in-flight background work instead of carrying it over when you background a session by pressing `←` or with [`/background`](/en/agent-view#from-inside-a-session). Claude Code asks you to confirm before backgrounding, then stops the tasks that would otherwise carry over. Requires Claude Code v2.1.195 or later |
| `CLAUDE_EFFORT` | Set automatically in Bash tool subprocesses and hook commands to the active [effort level](/en/model-config#adjust-effort-level) for the turn: `low`, `medium`, `high`, `xhigh`, or `max`. Ultracode is not a distinct level and reports as `xhigh`. Matches the `effort.level` field passed to [hooks](/en/hooks). Only set when the current model supports the effort parameter |
| `CLAUDE_ENABLE_BYTE_WATCHDOG` | Set to `1` to force-enable the byte-level streaming idle watchdog, or set to `0` to force-disable it. When unset, the watchdog is enabled by default for direct Anthropic API and [Claude Platform on AWS](/en/claude-platform-on-aws) connections. The byte watchdog aborts a connection when no bytes arrive on the wire for 180 seconds by default on direct Anthropic API connections, 300 seconds on Claude Platform on AWS and when enabled on Amazon Bedrock, or for the value of `CLAUDE_STREAM_IDLE_TIMEOUT_MS` when that is set, which is clamped to a minimum of 5 minutes, independent of the event-level watchdog |
| `CLAUDE_ENABLE_BYTE_WATCHDOG_BEDROCK` | Set to `1` to enable the byte-level streaming idle watchdog on Amazon Bedrock `vnd.amazon.eventstream` responses. Off by default. Configure the timeout with `CLAUDE_STREAM_IDLE_TIMEOUT_MS` |
| `CLAUDE_ENABLE_STREAM_WATCHDOG` | Set to `0` to force-disable the event-level streaming idle watchdog, or set to `1` to force-enable it. {/* min-version: 2.1.196 */}When unset, the watchdog is on by default for all providers. Before v2.1.196, the unset default was server-controlled on the direct Anthropic API and off on other providers. {/* min-version: 2.1.169 */}As of v2.1.169, providers other than the direct Anthropic API and Claude Platform on AWS also have a default-on 5-minute body idle timeout independent of this variable; see `API_FORCE_IDLE_TIMEOUT`. On Amazon Bedrock, you can also enable the independent byte-level watchdog with `CLAUDE_ENABLE_BYTE_WATCHDOG_BEDROCK`; the two run together when both are set. Configure the timeout with `CLAUDE_STREAM_IDLE_TIMEOUT_MS` |
| `CLAUDE_ENV_FILE` | Path to a shell script whose contents Claude Code runs before each Bash command in the same shell process, so exports in the file are visible to the command. Use to persist virtualenv or conda activation across commands. Also populated dynamically by [SessionStart](/en/hooks#persist-environment-variables), [Setup](/en/hooks#setup), [CwdChanged](/en/hooks#cwdchanged), and [FileChanged](/en/hooks#filechanged) hooks |
| `CLAUDE_REMOTE_CONTROL_SESSION_NAME_PREFIX` | Prefix for auto-generated [Remote Control](/en/remote-control) session names when no explicit name is provided. Defaults to your machine's hostname, producing names like `myhost-graceful-unicorn`. The `--remote-control-session-name-prefix` CLI flag sets the same value for a single invocation |
| `CLAUDE_STREAM_IDLE_TIMEOUT_MS` | Timeout in milliseconds before the streaming idle watchdog closes a stalled connection. When you set this variable explicitly, the minimum is `300000` (5 minutes); lower values are silently clamped to absorb extended thinking pauses and proxy buffering. When unset, the event-level watchdog defaults to 300 seconds and the byte-level watchdog defaults to 180 seconds on direct Anthropic API connections (300 seconds on Claude Platform on AWS and other providers). The unset 180-second byte-watchdog default is a separate value and is not subject to the 5-minute clamp. The body idle timeout described under `API_FORCE_IDLE_TIMEOUT` applies independently. On Amazon Bedrock, also applies when `CLAUDE_ENABLE_BYTE_WATCHDOG_BEDROCK=1` |
| `DEBUG` | Set to `1` to enable debug mode, equivalent to launching with [`--debug`](/en/cli-reference#cli-flags). Debug logs are written to `~/.claude/debug/.txt`, or to the path set by `CLAUDE_CODE_DEBUG_LOGS_DIR`. Only the truthy values `1`, `true`, `yes`, and `on` enable debug mode, so namespace patterns like `DEBUG=express:*` set for other tools do not trigger it |
| `DISABLE_AUTOUPDATER` | Set to `1` to disable automatic background updates. Manual `claude update` still works. Use `DISABLE_UPDATES` to block both |
| `DISABLE_AUTO_COMPACT` | Set to `1` to disable automatic compaction when approaching the context limit. The manual `/compact` command remains available. Use when you want explicit control over when compaction occurs |
| `DISABLE_COMPACT` | Set to `1` to disable all compaction: both automatic compaction and the manual `/compact` command |
| `DISABLE_COST_WARNINGS` | Set to `1` to disable cost warning messages |
| `DISABLE_DOCTOR_COMMAND` | Set to `1` to hide the [`/doctor`](/en/commands#all-commands) setup checkup skill and its `/checkup` alias. Useful for managed deployments where users shouldn't run setup diagnostics from a session. Doesn't affect the `claude doctor` terminal command. {/* min-version: 2.1.205 */}Before v2.1.205, this variable hid the `/doctor` diagnostics screen command |
| `DISABLE_ERROR_REPORTING` | Set to `1` to opt out of Sentry error reporting |
| `DISABLE_EXTRA_USAGE_COMMAND` | Set to `1` to hide the `/usage-credits` command that lets users purchase additional usage beyond rate limits |
| `DISABLE_FEEDBACK_COMMAND` | Set to `1` to disable the `/feedback` command. The older name `DISABLE_BUG_COMMAND` is also accepted |
| `DISABLE_GROWTHBOOK` | Set to `1` to disable GrowthBook feature-flag fetching and use code defaults for every flag. Telemetry event logging stays on unless `DISABLE_TELEMETRY` is also set |
| `DISABLE_INSTALLATION_CHECKS` | Set to `1` to disable installation warnings. Use only when manually managing the installation location, as this can mask issues with standard installations |
| `DISABLE_INSTALL_GITHUB_APP_COMMAND` | Set to `1` to hide the `/install-github-app` command. Already hidden when using third-party providers (Amazon Bedrock, Google Cloud's Agent Platform, or Microsoft Foundry) |
| `DISABLE_INTERLEAVED_THINKING` | Set to `1` to prevent sending the interleaved-thinking beta header. Useful when your LLM gateway or provider does not support [interleaved thinking](https://platform.claude.com/docs/en/build-with-claude/extended-thinking#interleaved-thinking) |
| `DISABLE_LOGIN_COMMAND` | Set to `1` to hide the `/login` command. Useful when authentication is handled externally via API keys or `apiKeyHelper` |
| `DISABLE_LOGOUT_COMMAND` | Set to `1` to hide the `/logout` command |
| `DISABLE_PROMPT_CACHING` | Set to `1` to disable [prompt caching](/en/prompt-caching#disable-prompt-caching) for all models (takes precedence over per-model settings) |
| `DISABLE_PROMPT_CACHING_FABLE` | Set to `1` to disable prompt caching for Fable models |
| `DISABLE_PROMPT_CACHING_HAIKU` | Set to `1` to disable prompt caching for Haiku models |
| `DISABLE_PROMPT_CACHING_OPUS` | Set to `1` to disable prompt caching for Opus models |
| `DISABLE_PROMPT_CACHING_SONNET` | Set to `1` to disable prompt caching for Sonnet models |
| `DISABLE_TELEMETRY` | Set to `1` to opt out of telemetry. Telemetry events do not include user data like code, file paths, or bash commands. Also disables feature-flag fetching with the same effect as `DISABLE_GROWTHBOOK`, so some flagged features may be unavailable |
| `DISABLE_UPDATES` | Set to `1` to block all updates including manual `claude update` and `claude install`. Stricter than `DISABLE_AUTOUPDATER`. Use when distributing Claude Code through your own channels and users should not self-update |
| `DISABLE_UPGRADE_COMMAND` | Set to `1` to hide the `/upgrade` command |
| `DO_NOT_TRACK` | Set to `1` to opt out of telemetry. Equivalent to setting `DISABLE_TELEMETRY`. Claude Code honors this as the cross-tool convention recognized by many developer CLIs |
| `ENABLE_CLAUDEAI_MCP_SERVERS` | Set to `false` to disable [claude.ai MCP servers](/en/mcp#use-mcp-servers-from-claude-ai) in Claude Code. Enabled by default for logged-in users. To disable per-project or per-org, set [`disableClaudeAiConnectors`](/en/settings#available-settings) in settings instead |
| `ENABLE_PROMPT_CACHING_1H` | Set to `1` to request a 1-hour [prompt cache TTL](/en/prompt-caching#cache-lifetime) instead of the default 5 minutes. Intended for API key, [Amazon Bedrock](/en/amazon-bedrock), [Google Cloud's Agent Platform](/en/google-vertex-ai), [Microsoft Foundry](/en/microsoft-foundry), and [Claude Platform on AWS](/en/claude-platform-on-aws) users. Subscription users within included usage receive 1-hour TTL automatically. 1-hour cache writes are billed at a higher rate |
| `ENABLE_PROMPT_CACHING_1H_BEDROCK` | Deprecated. Use `ENABLE_PROMPT_CACHING_1H` instead |
| `ENABLE_TOOL_SEARCH` | Controls [MCP tool search](/en/mcp#scale-with-mcp-tool-search). Unset: all MCP tools deferred by default, but loaded upfront on Google Cloud's Agent Platform or when `ANTHROPIC_BASE_URL` points to a non-first-party host. Values: `true` (always defer and send the beta header, requests fail on Google Cloud's Agent Platform models earlier than Sonnet 4.5 or Opus 4.5, or on proxies that do not support `tool_reference`), `auto` (threshold mode: load upfront if tools fit within 10% of context), `auto:N` (custom threshold, e.g., `auto:5` for 5%), `false` (load all upfront) |
| `FALLBACK_FOR_ALL_PRIMARY_MODELS` | Set to any non-empty value to make all models, not only Opus, stop retrying with a repeated-overload error when no fallback model is configured. {/* min-version: 2.1.160 */}As of v2.1.160, a configured [fallback model chain](/en/model-config#fallback-model-chains) triggers on repeated overload errors for any primary model, so this variable does not affect switching to a fallback model |
| `FORCE_AUTOUPDATE_PLUGINS` | Set to `1` to force plugin auto-updates even when the main auto-updater is disabled via `DISABLE_AUTOUPDATER` |
| `FORCE_PROMPT_CACHING_5M` | Set to `1` to force the 5-minute prompt cache TTL even when 1-hour TTL would otherwise apply. Overrides `ENABLE_PROMPT_CACHING_1H` |
| `HTTP_PROXY` | Specify HTTP proxy server for network connections |
| `HTTPS_PROXY` | Specify HTTPS proxy server for network connections |
| `IS_DEMO` | Set to `1` to enable demo mode: hides your email and organization name from the header and `/status` output, and skips onboarding. Useful when streaming or recording a session |
| `MAX_MCP_OUTPUT_TOKENS` | Maximum number of tokens allowed in MCP tool responses. Claude Code displays a warning when output exceeds 10,000 tokens. Tools that declare [`anthropic/maxResultSizeChars`](/en/mcp#raise-the-limit-for-a-specific-tool) use that character limit for text content instead, but image content from those tools is still subject to this variable (default: 25000) |
| `MAX_STRUCTURED_OUTPUT_RETRIES` | Number of times to retry when the model's response fails validation against the [`--json-schema`](/en/cli-reference#cli-flags) in non-interactive mode (the `-p` flag). Defaults to 5 |
| `MAX_THINKING_TOKENS` | Override the [extended thinking](https://platform.claude.com/docs/en/build-with-claude/extended-thinking) token budget. The ceiling is the model's [max output tokens](https://platform.claude.com/docs/en/about-claude/models/overview#latest-models-comparison) minus one. Set to `0` to disable thinking on the Anthropic API except on Fable 5, which cannot have thinking turned off. On [third-party providers](/en/third-party-integrations), `0` omits the `thinking` parameter instead, and models with [adaptive reasoning](/en/model-config#adjust-effort-level) may still think. For nonzero values on adaptive reasoning models, the budget is ignored unless adaptive reasoning is disabled via `CLAUDE_CODE_DISABLE_ADAPTIVE_THINKING` |
| `MCP_CLIENT_SECRET` | OAuth client secret for MCP servers that require [pre-configured credentials](/en/mcp#use-pre-configured-oauth-credentials). Avoids the interactive prompt when adding a server with `--client-secret` |
| `MCP_CONNECTION_NONBLOCKING` | Controls whether startup waits for MCP servers to connect before the first query. {/* min-version: 2.1.142 */}As of Claude Code v2.1.142, MCP startup is non-blocking by default: servers connect in the background and their tools become available as they finish. Set to `0` to restore the blocking 5-second connection wait. Servers configured with [`alwaysLoad: true`](/en/mcp#exempt-a-server-from-deferral) still block startup regardless, since their tools must be present when the first prompt is built |
| `MCP_CONNECT_TIMEOUT_MS` | How long blocking MCP startup waits, in milliseconds, for the connection batch before snapshotting the tool list (default: 5000). Applies when `MCP_CONNECTION_NONBLOCKING=0` or for servers marked [`alwaysLoad: true`](/en/mcp#exempt-a-server-from-deferral). Servers still pending at the deadline keep connecting in the background but won't appear until the next query. Distinct from `MCP_TIMEOUT`, which bounds an individual server's connect attempt |
| `MCP_OAUTH_CALLBACK_PORT` | Fixed port for the OAuth redirect callback, as an alternative to `--callback-port` when adding an MCP server with [pre-configured credentials](/en/mcp#use-pre-configured-oauth-credentials) |
| `MCP_REMOTE_SERVER_CONNECTION_BATCH_SIZE` | Maximum number of remote MCP servers (HTTP/SSE) to connect in parallel during startup (default: 20) |
| `MCP_SERVER_CONNECTION_BATCH_SIZE` | Maximum number of local MCP servers (stdio) to connect in parallel during startup (default: 3) |
| `MCP_TIMEOUT` | Timeout in milliseconds for MCP server startup (default: 30000, or 30 seconds) |
| `MCP_TOOL_TIMEOUT` | Timeout in milliseconds for MCP tool execution (default: 100000000, about 28 hours). A per-server `timeout` field in `.mcp.json` overrides this for that server. {/* min-version: 2.1.203 */}A per-server `timeout` of at least 1000 also sets the minimum idle window for that server's tool calls, so `CLAUDE_CODE_MCP_TOOL_IDLE_TIMEOUT` never aborts them sooner; this floor requires Claude Code v2.1.203 or later. For the env variable, values below 1000 are floored to one second; for the per-server field, values below 1000 are ignored |
| `NO_PROXY` | List of domains and IPs to which requests will be directly issued, bypassing proxy |
| `OTEL_LOG_ASSISTANT_RESPONSES` | {/* min-version: 2.1.193 */}Set to `1` to include the model's response text on `assistant_response` OpenTelemetry log events. When unset, the value of `OTEL_LOG_USER_PROMPTS` is used instead. Set to `0` to keep responses redacted even when `OTEL_LOG_USER_PROMPTS` is set. Requires Claude Code v2.1.193 or later. See [Monitoring](/en/monitoring-usage#assistant-response-event) |
| `OTEL_LOG_RAW_API_BODIES` | Emit Anthropic Messages API request and response JSON as `api_request_body` / `api_response_body` log events. Set to `1` for inline bodies truncated at 60 KB, or `file:` to write untruncated bodies to disk and emit a `body_ref` path instead. Disabled by default; bodies include the entire conversation history. See [Monitoring](/en/monitoring-usage#api-request-body-event) |
| `OTEL_LOG_TOOL_CONTENT` | Set to `1` to include tool input and output content in OpenTelemetry span events. Disabled by default to protect sensitive data. See [Monitoring](/en/monitoring-usage) |
| `OTEL_LOG_TOOL_DETAILS` | Set to `1` to include tool input arguments, MCP server names, user-authored workflow names, raw error strings on tool failures, the refusal `category` on `api_refusal` events, and other tool details in OpenTelemetry traces and logs. Disabled by default to protect PII. See [Monitoring](/en/monitoring-usage) |
| `OTEL_LOG_USER_PROMPTS` | Set to `1` to include user prompt text in OpenTelemetry traces and logs. Disabled by default (prompts are redacted). See [Monitoring](/en/monitoring-usage) |
| `OTEL_METRICS_INCLUDE_ACCOUNT_UUID` | Set to `false` to exclude account UUID from metrics attributes (default: included). See [Monitoring](/en/monitoring-usage) |
| `OTEL_METRICS_INCLUDE_ENTRYPOINT` | {/* min-version: 2.1.152 */}Set to `true` to include the session entrypoint in metrics attributes (default: excluded). Added in v2.1.152. See [Monitoring](/en/monitoring-usage) |
| `OTEL_METRICS_INCLUDE_RESOURCE_ATTRIBUTES` | {/* min-version: 2.1.161 */}As of v2.1.161, Claude Code attaches `OTEL_RESOURCE_ATTRIBUTES` keys to metric datapoint labels. Set to `false` to exclude them (default: included). See [Monitoring](/en/monitoring-usage#multi-team-organization-support) |
| `OTEL_METRICS_INCLUDE_SESSION_ID` | Set to `false` to exclude session ID from metrics attributes (default: included). See [Monitoring](/en/monitoring-usage) |
| `OTEL_METRICS_INCLUDE_VERSION` | Set to `true` to include Claude Code version in metrics attributes (default: excluded). See [Monitoring](/en/monitoring-usage) |
| `SLASH_COMMAND_TOOL_CHAR_BUDGET` | Override the character budget for skill metadata shown to the [Skill tool](/en/skills#control-who-invokes-a-skill). The budget scales dynamically at 1% of the context window, with a fallback of 8,000 characters. Legacy name kept for backwards compatibility |
| `TASK_MAX_OUTPUT_LENGTH` | Maximum number of characters in [subagent](/en/sub-agents) output before truncation (default: 32000, maximum: 160000). When truncated, the full output is saved to disk and the path is included in the truncated response |
| `USE_BUILTIN_RIPGREP` | Set to `0` to use system-installed `rg` instead of `rg` included with Claude Code |
| `VERTEX_REGION_CLAUDE_3_5_HAIKU` | Override region for Claude 3.5 Haiku when using Google Cloud's Agent Platform |
| `VERTEX_REGION_CLAUDE_3_5_SONNET` | Override region for Claude 3.5 Sonnet when using Google Cloud's Agent Platform |
| `VERTEX_REGION_CLAUDE_3_7_SONNET` | Override region for Claude 3.7 Sonnet when using Google Cloud's Agent Platform |
| `VERTEX_REGION_CLAUDE_4_0_OPUS` | Override region for Claude 4.0 Opus when using Google Cloud's Agent Platform |
| `VERTEX_REGION_CLAUDE_4_0_SONNET` | Override region for Claude 4.0 Sonnet when using Google Cloud's Agent Platform |
| `VERTEX_REGION_CLAUDE_4_1_OPUS` | Override region for Claude 4.1 Opus when using Google Cloud's Agent Platform |
| `VERTEX_REGION_CLAUDE_4_5_OPUS` | Override region for Claude Opus 4.5 when using Google Cloud's Agent Platform |
| `VERTEX_REGION_CLAUDE_4_5_SONNET` | Override region for Claude Sonnet 4.5 when using Google Cloud's Agent Platform |
| `VERTEX_REGION_CLAUDE_4_6_OPUS` | Override region for Claude Opus 4.6 when using Google Cloud's Agent Platform |
| `VERTEX_REGION_CLAUDE_4_6_SONNET` | Override region for Claude Sonnet 4.6 when using Google Cloud's Agent Platform |
| `VERTEX_REGION_CLAUDE_4_7_OPUS` | {/* min-version: 2.1.111 */}Override region for Claude Opus 4.7 when using Google Cloud's Agent Platform. Added in v2.1.111 |
| `VERTEX_REGION_CLAUDE_4_8_OPUS` | {/* min-version: 2.1.154 */}Override region for Claude Opus 4.8 when using Google Cloud's Agent Platform. Added in v2.1.154 |
| `VERTEX_REGION_CLAUDE_5_SONNET` | {/* min-version: 2.1.197 */}Override region for Claude Sonnet 5 when using Google Cloud's Agent Platform. Added in v2.1.197 |
| `VERTEX_REGION_CLAUDE_FABLE_5` | {/* min-version: 2.1.170 */}Override region for Claude Fable 5 when using Google Cloud's Agent Platform. Added in v2.1.170 |
| `VERTEX_REGION_CLAUDE_HAIKU_4_5` | Override region for Claude Haiku 4.5 when using Google Cloud's Agent Platform |
Standard OpenTelemetry exporter variables (`OTEL_METRICS_EXPORTER`, `OTEL_LOGS_EXPORTER`, `OTEL_EXPORTER_OTLP_ENDPOINT`, `OTEL_EXPORTER_OTLP_PROTOCOL`, `OTEL_EXPORTER_OTLP_HEADERS`, `OTEL_METRIC_EXPORT_INTERVAL`, `OTEL_RESOURCE_ATTRIBUTES`, and signal-specific variants) are also supported. See [Monitoring](/en/monitoring-usage) for configuration details.
## See also
* [Settings](/en/settings): all `settings.json` configuration, including the `env` key
* [CLI reference](/en/cli-reference): launch-time flags
* [Network configuration](/en/network-config): proxy and TLS setup
* [Monitoring](/en/monitoring-usage): OpenTelemetry configuration