67The file you choose controls who the variables apply to:67The file you choose controls who the variables apply to:
68 68
69| File | Applies to |69| File | Applies to |
70| :---------------------------- | :----------------------------------------------------------- |70| :---------------------------- | :---------------------------------------------------------------------------- |
71| `~/.claude/settings.json` | You, in every project |71| `~/.claude/settings.json` | You, in every project |
72| `.claude/settings.json` | Everyone working in the project, checked into source control |72| `.claude/settings.json` | Everyone working in the project, checked into source control |
73| `.claude/settings.local.json` | You, in this project only, not checked in |73| `.claude/settings.local.json` | You, in this project only (add it to your gitignore if you create it by hand) |
74| Managed settings | Everyone in your organization, deployed by an admin |74| Managed settings | Everyone in your organization, deployed by an admin |
75 75
76See [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.76See [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.
86## Variables86## Variables
87 87
88| Variable | Purpose |88| Variable | Purpose |
89| :------------------------------------------------------ | :---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |89| :------------------------------------------------------ | :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
90| `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` |90| `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` |
91| `ANTHROPIC_AUTH_TOKEN` | Custom value for the `Authorization` header (the value you set here will be prefixed with `Bearer `) |91| `ANTHROPIC_AUTH_TOKEN` | Custom value for the `Authorization` header (the value you set here will be prefixed with `Bearer `) |
92| `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 |92| `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 |
102| `ANTHROPIC_CUSTOM_MODEL_OPTION_DESCRIPTION` | Display description for the custom model entry in the `/model` picker. Defaults to `Custom model (<model-id>)` when not set |102| `ANTHROPIC_CUSTOM_MODEL_OPTION_DESCRIPTION` | Display description for the custom model entry in the `/model` picker. Defaults to `Custom model (<model-id>)` when not set |
103| `ANTHROPIC_CUSTOM_MODEL_OPTION_NAME` | Display name for the custom model entry in the `/model` picker. Defaults to the model ID when not set |103| `ANTHROPIC_CUSTOM_MODEL_OPTION_NAME` | Display name for the custom model entry in the `/model` picker. Defaults to the model ID when not set |
104| `ANTHROPIC_CUSTOM_MODEL_OPTION_SUPPORTED_CAPABILITIES` | See [Model configuration](/en/model-config#customize-pinned-model-display-and-capabilities) |104| `ANTHROPIC_CUSTOM_MODEL_OPTION_SUPPORTED_CAPABILITIES` | See [Model configuration](/en/model-config#customize-pinned-model-display-and-capabilities) |
105| `ANTHROPIC_DEFAULT_FABLE_MODEL` | See [Model configuration](/en/model-config#environment-variables) |
106| `ANTHROPIC_DEFAULT_FABLE_MODEL_DESCRIPTION` | See [Model configuration](/en/model-config#customize-pinned-model-display-and-capabilities) |
107| `ANTHROPIC_DEFAULT_FABLE_MODEL_NAME` | See [Model configuration](/en/model-config#customize-pinned-model-display-and-capabilities) |
108| `ANTHROPIC_DEFAULT_FABLE_MODEL_SUPPORTED_CAPABILITIES` | See [Model configuration](/en/model-config#customize-pinned-model-display-and-capabilities) |
105| `ANTHROPIC_DEFAULT_HAIKU_MODEL` | See [Model configuration](/en/model-config#environment-variables) |109| `ANTHROPIC_DEFAULT_HAIKU_MODEL` | See [Model configuration](/en/model-config#environment-variables) |
106| `ANTHROPIC_DEFAULT_HAIKU_MODEL_DESCRIPTION` | See [Model configuration](/en/model-config#customize-pinned-model-display-and-capabilities) |110| `ANTHROPIC_DEFAULT_HAIKU_MODEL_DESCRIPTION` | See [Model configuration](/en/model-config#customize-pinned-model-display-and-capabilities) |
107| `ANTHROPIC_DEFAULT_HAIKU_MODEL_NAME` | See [Model configuration](/en/model-config#customize-pinned-model-display-and-capabilities) |111| `ANTHROPIC_DEFAULT_HAIKU_MODEL_NAME` | See [Model configuration](/en/model-config#customize-pinned-model-display-and-capabilities) |
123| `ANTHROPIC_VERTEX_BASE_URL` | Override the Vertex AI endpoint URL. Use for custom Vertex endpoints or when routing through an [LLM gateway](/en/llm-gateway). See [Google Vertex AI](/en/google-vertex-ai) |127| `ANTHROPIC_VERTEX_BASE_URL` | Override the Vertex AI endpoint URL. Use for custom Vertex endpoints or when routing through an [LLM gateway](/en/llm-gateway). See [Google Vertex AI](/en/google-vertex-ai) |
124| `ANTHROPIC_VERTEX_PROJECT_ID` | GCP project ID for Vertex AI requests. Overridden by `GCLOUD_PROJECT`, `GOOGLE_CLOUD_PROJECT`, or the project in your `GOOGLE_APPLICATION_CREDENTIALS` credential file. See [Google Vertex AI](/en/google-vertex-ai) |128| `ANTHROPIC_VERTEX_PROJECT_ID` | GCP project ID for Vertex AI requests. Overridden by `GCLOUD_PROJECT`, `GOOGLE_CLOUD_PROJECT`, or the project in your `GOOGLE_APPLICATION_CREDENTIALS` credential file. See [Google Vertex AI](/en/google-vertex-ai) |
125| `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 |129| `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 |
130| `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 [Vertex AI](/en/google-vertex-ai), [Foundry](/en/microsoft-foundry), [Mantle](/en/amazon-bedrock#use-the-mantle-endpoint), [Bedrock](/en/amazon-bedrock), and gateway connections, so a stalled stream aborts instead of hanging. As of v2.1.169 |
126| `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 |131| `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 |
127| `AWS_BEARER_TOKEN_BEDROCK` | Bedrock API key for authentication (see [Bedrock API keys](https://aws.amazon.com/blogs/machine-learning/accelerate-ai-development-with-amazon-bedrock-api-keys/)) |132| `AWS_BEARER_TOKEN_BEDROCK` | Bedrock API key for authentication (see [Bedrock API keys](https://aws.amazon.com/blogs/machine-learning/accelerate-ai-development-with-amazon-bedrock-api-keys/)) |
128| `BASH_DEFAULT_TIMEOUT_MS` | Default timeout for long-running bash commands (default: 120000, or 2 minutes) |133| `BASH_DEFAULT_TIMEOUT_MS` | Default timeout for long-running bash commands (default: 120000, or 2 minutes) |
139| `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 |144| `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 |
140| `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 |145| `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 |
141| `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 |146| `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 |
147| `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 |
142| `CLAUDE_CODE_API_KEY_HELPER_TTL_MS` | Interval in milliseconds at which credentials should be refreshed (when using [`apiKeyHelper`](/en/settings#available-settings)) |148| `CLAUDE_CODE_API_KEY_HELPER_TTL_MS` | Interval in milliseconds at which credentials should be refreshed (when using [`apiKeyHelper`](/en/settings#available-settings)) |
143| `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). Anthropic API caching is unaffected |149| `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). Anthropic API caching is unaffected |
144| `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. 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 |150| `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. 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 |
150| `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/<session-id>.txt` |156| `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/<session-id>.txt` |
151| `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 |157| `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 |
152| `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. Useful for enterprise environments with compliance requirements |158| `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. Useful for enterprise environments with compliance requirements |
153| `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 Opus 4.7 and later, which always use adaptive reasoning |159| `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, or on Opus 4.7 and later, which always use adaptive reasoning |
160| `CLAUDE_CODE_DISABLE_ADVISOR_TOOL` | {/* min-version: 2.1.98 */}Set to `1` to disable the [advisor tool](/en/advisor). The `/advisor` command and `--advisor` flag become unavailable and any configured `advisorModel` is ignored. Requires Claude Code v2.1.98 or later |
154| `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 |161| `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 |
155| `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 |162| `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 |
156| `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 |163| `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 |
157| `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 |164| `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 |
158| `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 |165| `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 |
166| `CLAUDE_CODE_DISABLE_BUNDLED_SKILLS` | Set to `1` to disable the [skills](/en/skills) and workflows that ship with Claude Code: bundled skills and workflows are removed entirely, while built-in slash commands like `/init` stay typable but are hidden from the model. Skills from plugins, `.claude/skills/`, and `.claude/commands/` are unaffected. Equivalent to the [`disableBundledSkills`](/en/settings#available-settings) setting; `0` does not override it |
159| `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 |167| `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 |
160| `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 |168| `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 |
161| `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. |169| `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. |
170| `CLAUDE_CODE_DISABLE_OFFICIAL_MARKETPLACE_AUTOINSTALL` | Set to `1` to skip automatic addition of the official plugin marketplace on first run |178| `CLAUDE_CODE_DISABLE_OFFICIAL_MARKETPLACE_AUTOINSTALL` | Set to `1` to skip automatic addition of the official plugin marketplace on first run |
171| `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 |179| `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 |
172| `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 |180| `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 |
173| `CLAUDE_CODE_DISABLE_THINKING` | Set to `1` to force-disable [extended thinking](https://platform.claude.com/docs/en/build-with-claude/extended-thinking) regardless of model support or other settings. More direct than `MAX_THINKING_TOKENS=0` |181| `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 |
174| `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 |182| `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 |
175| `CLAUDE_CODE_DISABLE_WORKFLOWS` | Set to `1` to disable [workflows](/en/workflows#turn-workflows-off). Equivalent to the [`disableWorkflows`](/en/settings#available-settings) setting |183| `CLAUDE_CODE_DISABLE_WORKFLOWS` | Set to `1` to disable [workflows](/en/workflows#turn-workflows-off). Equivalent to the [`disableWorkflows`](/en/settings#available-settings) setting |
176| `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) |184| `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) |
188| `CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS` | Set to `1` to enable [agent teams](/en/agent-teams). Agent teams are experimental and disabled by default |196| `CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS` | Set to `1` to enable [agent teams](/en/agent-teams). Agent teams are experimental and disabled by default |
189| `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 |197| `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 |
190| `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 |198| `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 |
199| `CLAUDE_CODE_FORCE_SESSION_PERSISTENCE` | {/* max-version: 2.1.169 */}Removed in v2.1.170. This variable forced transcript persistence when an inherited `CLAUDECODE` value caused a top-level session to be misclassified as nested. The nested-session detection it overrode was removed in v2.1.170, so the variable no longer applies |
191| `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 |200| `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 |
192| `CLAUDE_CODE_FORK_SUBAGENT` | Set to `1` to make [forked subagents](/en/sub-agents#fork-the-current-conversation) the model's default, or `0` to disable them, overriding any server-side rollout. When enabled, Claude spawns a fork, a subagent that inherits the full conversation context instead of starting fresh, whenever it would otherwise 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` |201| `CLAUDE_CODE_FORK_SUBAGENT` | Set to `1` to make [forked subagents](/en/sub-agents#fork-the-current-conversation) the model's default, or `0` to disable them, overriding any server-side rollout. When enabled, Claude spawns a fork, a subagent that inherits the full conversation context instead of starting fresh, whenever it would otherwise 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` |
193| `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) |202| `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) |
229| `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 artifacts back to the session](/en/claude-code-on-the-web#link-artifacts-back-to-the-session) |238| `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 artifacts back to the session](/en/claude-code-on-the-web#link-artifacts-back-to-the-session) |
230| `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 |239| `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 |
231| `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 |240| `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 |
241| `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 |
232| `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 |242| `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 |
233| `CLAUDE_CODE_SCROLL_SPEED` | Set the mouse wheel scroll multiplier in [fullscreen rendering](/en/fullscreen#mouse-wheel-scrolling). Accepts values from 1 to 20. 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 |243| `CLAUDE_CODE_SCROLL_SPEED` | Set the mouse wheel scroll multiplier in [fullscreen rendering](/en/fullscreen#mouse-wheel-scrolling). Accepts values from 1 to 20. 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 |
234| `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 |244| `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 |
235| `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 <session-id>` 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 |245| `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 <session-id>` 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 |
236| `CLAUDE_CODE_SHELL` | Override automatic shell detection. Useful when your login shell differs from your preferred working shell (for example, `bash` vs `zsh`) |246| `CLAUDE_CODE_SHELL` | Override automatic shell detection. Useful when your login shell differs from your preferred working shell (for example, `bash` vs `zsh`) |
237| `CLAUDE_CODE_SHELL_PREFIX` | Command prefix that wraps shell commands Claude Code spawns: Bash tool calls, [hook](/en/hooks) commands, and stdio [MCP server](/en/mcp) startup commands. Useful for logging or auditing. Example: setting `/path/to/logger.sh` runs each command as `/path/to/logger.sh <command>` |247| `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 '<command>'`. 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 <package>`. For Bash tool calls, `$1` contains the full shell invocation Claude Code assembles, including environment setup, not only the command Claude ran |
238| `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) |248| `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) |
239| `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 |249| `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 |
240| `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 |250| `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 |
248| `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 |258| `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 |
249| `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 |259| `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 |
250| `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 |260| `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 |
251| `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. Set automatically in [Claude Code on the web](/en/claude-code-on-the-web) sessions. Requires claude.ai authentication |261| `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 |
252| `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 |262| `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 |
253| `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 |263| `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 |
254| `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 |264| `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 |
265| `CLAUDE_CODE_USE_VERTEX` | Use [Vertex](/en/google-vertex-ai) |275| `CLAUDE_CODE_USE_VERTEX` | Use [Vertex](/en/google-vertex-ai) |
266| `CLAUDE_CONFIG_DIR` | Override the configuration directory (default: `~/.claude`). All settings, credentials, session history, and plugins are stored under this path. Useful for running multiple accounts side by side: for example, `alias claude-work='CLAUDE_CONFIG_DIR=~/.claude-work claude'` |276| `CLAUDE_CONFIG_DIR` | Override the configuration directory (default: `~/.claude`). All settings, credentials, session history, and plugins are stored under this path. Useful for running multiple accounts side by side: for example, `alias claude-work='CLAUDE_CONFIG_DIR=~/.claude-work claude'` |
267| `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 |277| `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 |
268| `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 Anthropic API connections. The byte watchdog aborts a connection when no bytes arrive on the wire for the duration set by `CLAUDE_STREAM_IDLE_TIMEOUT_MS`, with a minimum of 5 minutes, independent of the event-level watchdog |278| `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 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 |
269| `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` |279| `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` |
270| `CLAUDE_ENABLE_STREAM_WATCHDOG` | Set to `1` to enable the event-level streaming idle watchdog. Off by default. Applies to all providers, including Bedrock. For Vertex and Foundry, this is the only idle watchdog available. On 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` |280| `CLAUDE_ENABLE_STREAM_WATCHDOG` | Set to `1` to force-enable the event-level streaming idle watchdog, or set to `0` to force-disable it. When unset, the default is 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 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` |
271| `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 |281| `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 |
272| `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 |282| `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 |
273| `CLAUDE_STREAM_IDLE_TIMEOUT_MS` | Timeout in milliseconds before the streaming idle watchdog closes a stalled connection. Default and minimum `300000` (5 minutes) for both the byte-level and event-level watchdogs; lower values are silently clamped to absorb extended thinking pauses and proxy buffering. For third-party providers, requires `CLAUDE_ENABLE_STREAM_WATCHDOG=1`. On Bedrock, also applies when `CLAUDE_ENABLE_BYTE_WATCHDOG_BEDROCK=1` |283| `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. For the event-level watchdog on third-party providers, requires `CLAUDE_ENABLE_STREAM_WATCHDOG=1`; the body idle timeout described under `API_FORCE_IDLE_TIMEOUT` applies independently. On Bedrock, also applies when `CLAUDE_ENABLE_BYTE_WATCHDOG_BEDROCK=1` |
274| `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/<session-id>.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 |284| `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/<session-id>.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 |
275| `DISABLE_AUTOUPDATER` | Set to `1` to disable automatic background updates. Manual `claude update` still works. Use `DISABLE_UPDATES` to block both |285| `DISABLE_AUTOUPDATER` | Set to `1` to disable automatic background updates. Manual `claude update` still works. Use `DISABLE_UPDATES` to block both |
276| `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 |286| `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 |
287| `DISABLE_LOGIN_COMMAND` | Set to `1` to hide the `/login` command. Useful when authentication is handled externally via API keys or `apiKeyHelper` |297| `DISABLE_LOGIN_COMMAND` | Set to `1` to hide the `/login` command. Useful when authentication is handled externally via API keys or `apiKeyHelper` |
288| `DISABLE_LOGOUT_COMMAND` | Set to `1` to hide the `/logout` command |298| `DISABLE_LOGOUT_COMMAND` | Set to `1` to hide the `/logout` command |
289| `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) |299| `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) |
300| `DISABLE_PROMPT_CACHING_FABLE` | Set to `1` to disable prompt caching for Fable models |
290| `DISABLE_PROMPT_CACHING_HAIKU` | Set to `1` to disable prompt caching for Haiku models |301| `DISABLE_PROMPT_CACHING_HAIKU` | Set to `1` to disable prompt caching for Haiku models |
291| `DISABLE_PROMPT_CACHING_OPUS` | Set to `1` to disable prompt caching for Opus models |302| `DISABLE_PROMPT_CACHING_OPUS` | Set to `1` to disable prompt caching for Opus models |
292| `DISABLE_PROMPT_CACHING_SONNET` | Set to `1` to disable prompt caching for Sonnet models |303| `DISABLE_PROMPT_CACHING_SONNET` | Set to `1` to disable prompt caching for Sonnet models |
298| `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, [Bedrock](/en/amazon-bedrock), [Vertex](/en/google-vertex-ai), [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 |309| `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, [Bedrock](/en/amazon-bedrock), [Vertex](/en/google-vertex-ai), [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 |
299| `ENABLE_PROMPT_CACHING_1H_BEDROCK` | Deprecated. Use `ENABLE_PROMPT_CACHING_1H` instead |310| `ENABLE_PROMPT_CACHING_1H_BEDROCK` | Deprecated. Use `ENABLE_PROMPT_CACHING_1H` instead |
300| `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 Vertex AI or when `ANTHROPIC_BASE_URL` points to a non-first-party host. Values: `true` (always defer and send the beta header, requests fail on Vertex AI 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) |311| `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 Vertex AI or when `ANTHROPIC_BASE_URL` points to a non-first-party host. Values: `true` (always defer and send the beta header, requests fail on Vertex AI 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) |
301| `FALLBACK_FOR_ALL_PRIMARY_MODELS` | Set to any non-empty value to trigger fallback to [`--fallback-model`](/en/cli-reference#cli-flags) after repeated overload errors on any primary model. By default, only Opus models trigger the fallback |312| `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 |
302| `FORCE_AUTOUPDATE_PLUGINS` | Set to `1` to force plugin auto-updates even when the main auto-updater is disabled via `DISABLE_AUTOUPDATER` |313| `FORCE_AUTOUPDATE_PLUGINS` | Set to `1` to force plugin auto-updates even when the main auto-updater is disabled via `DISABLE_AUTOUPDATER` |
303| `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` |314| `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` |
304| `HTTP_PROXY` | Specify HTTP proxy server for network connections |315| `HTTP_PROXY` | Specify HTTP proxy server for network connections |
306| `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 |317| `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 |
307| `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) |318| `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) |
308| `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 |319| `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 |
309| `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 entirely. On models with [adaptive reasoning](/en/model-config#adjust-effort-level), the budget is ignored unless adaptive reasoning is disabled via `CLAUDE_CODE_DISABLE_ADAPTIVE_THINKING` |320| `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` |
310| `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` |321| `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` |
311| `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 |322| `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 |
312| `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 |323| `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 |
339| `VERTEX_REGION_CLAUDE_4_6_OPUS` | Override region for Claude Opus 4.6 when using Vertex AI |350| `VERTEX_REGION_CLAUDE_4_6_OPUS` | Override region for Claude Opus 4.6 when using Vertex AI |
340| `VERTEX_REGION_CLAUDE_4_6_SONNET` | Override region for Claude Sonnet 4.6 when using Vertex AI |351| `VERTEX_REGION_CLAUDE_4_6_SONNET` | Override region for Claude Sonnet 4.6 when using Vertex AI |
341| `VERTEX_REGION_CLAUDE_4_7_OPUS` | {/* min-version: 2.1.111 */}Override region for Claude Opus 4.7 when using Vertex AI. Added in v2.1.111 |352| `VERTEX_REGION_CLAUDE_4_7_OPUS` | {/* min-version: 2.1.111 */}Override region for Claude Opus 4.7 when using Vertex AI. Added in v2.1.111 |
353| `VERTEX_REGION_CLAUDE_4_8_OPUS` | {/* min-version: 2.1.154 */}Override region for Claude Opus 4.8 when using Vertex AI. Added in v2.1.154 |
354| `VERTEX_REGION_CLAUDE_FABLE_5` | {/* min-version: 2.1.170 */}Override region for Claude Fable 5 when using Vertex AI. Added in v2.1.170 |
342| `VERTEX_REGION_CLAUDE_HAIKU_4_5` | Override region for Claude Haiku 4.5 when using Vertex AI |355| `VERTEX_REGION_CLAUDE_HAIKU_4_5` | Override region for Claude Haiku 4.5 when using Vertex AI |
343 356
344Standard 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.357Standard 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.
