--- title: "Environment variables" description: "> ## 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." type: skill canonical_url: https://claudary.paisolsolutions.com/skills/env-vars source: "Claudary" difficulty: intermediate author: "Claude Code Knowledge Pack" date: 2026-07-10T11:24:14.067Z license: CC-BY-4.0 attribution: "Environment variables — Claudary (https://claudary.paisolsolutions.com/skills/env-vars)" --- # Environment variables > ## 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. ## Overview > ## 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 > Complete reference for environment variables that control Claude Code behavior. Claude Code supports the following environment variables to control its behavior. Set them in your shell before launching `claude`, or configure them in [`settings.json`](/en/settings#available-settings) under the `env` key to apply them to every session or roll them out across your team. | 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_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 | | `ANTHROPIC_BEDROCK_BASE_URL` | Override the Bedrock endpoint URL. Use for custom 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 Bedrock Mantle endpoint URL. See [Mantle endpoint](/en/amazon-bedrock#use-the-mantle-endpoint) | | `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_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) --- Source: [Claudary](https://claudary.paisolsolutions.com/skills/env-vars) · https://claudary.paisolsolutions.com