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- Type: String (model ID)
- Default: Determined by provider and tier
- Description: Override the default Claude model for all API calls. Validated against known model IDs during startup. Can also be set via CLI flag or settings file.
- Example:
export ANTHROPIC_MODEL=claude-sonnet-4-6
- See also: ANTHROPIC_DEFAULT_OPUS_MODEL, ANTHROPIC_DEFAULT_SONNET_MODEL, ANTHROPIC_DEFAULT_HAIKU_MODEL
- Type: String (model ID)
- Default:
opus-4.6 (first-party); opus-4.6 (third-party providers)
- Description: Override the default Opus model ID. Used when selecting a high-capability model.
- Example:
export ANTHROPIC_DEFAULT_OPUS_MODEL=claude-opus-4-1
- Type: String (display name)
- Default: Unspecified
- Description: Display name for custom Opus model override shown in the model selector UI.
- Example:
export ANTHROPIC_DEFAULT_OPUS_MODEL_NAME="Opus (Internal)"
- Type: String (description text)
- Default: Unspecified
- Description: Description text for custom Opus model override displayed in the model selector.
- Example:
export ANTHROPIC_DEFAULT_OPUS_MODEL_DESCRIPTION="High-capability reasoning model for complex tasks"
- Type: String (model ID)
- Default:
sonnet-4.6 (first-party); sonnet-4.5 (third-party providers)
- Description: Override the default Sonnet model ID. Used when selecting a balanced model.
- Example:
export ANTHROPIC_DEFAULT_SONNET_MODEL=claude-sonnet-4-6
- Type: String (display name)
- Default: Unspecified
- Description: Display name for custom Sonnet model override in the model selector.
- Example:
export ANTHROPIC_DEFAULT_SONNET_MODEL_NAME="Sonnet (Production)"
- Type: String (description text)
- Default: Unspecified
- Description: Description text for custom Sonnet model override.
- Example:
export ANTHROPIC_DEFAULT_SONNET_MODEL_DESCRIPTION="Balanced model for general-purpose coding"
- Type: String (model ID)
- Default:
haiku-4.5 (falls back if not set)
- Description: Override the default Haiku (small/fast) model ID. Used for non-first-party providers.
- Example:
export ANTHROPIC_DEFAULT_HAIKU_MODEL=claude-haiku-3-5
- Type: String (display name)
- Default: Unspecified
- Description: Display name for custom Haiku model override.
- Example:
export ANTHROPIC_DEFAULT_HAIKU_MODEL_NAME="Haiku (Fast)"
- Type: String (description text)
- Default: Unspecified
- Description: Description text for custom Haiku model override.
- Example:
export ANTHROPIC_DEFAULT_HAIKU_MODEL_DESCRIPTION="Lightweight model for quick operations"
- Type: String (model ID)
- Default: Unspecified
- Description: Add a custom model ID to the model selector dropdown. Validated during model selection.
- Example:
export ANTHROPIC_CUSTOM_MODEL_OPTION=my-fine-tuned-model-v2
- Type: String (display name)
- Default: Unspecified
- Description: Display name for the custom model option in the selector.
- Example:
export ANTHROPIC_CUSTOM_MODEL_OPTION_NAME="My Fine-Tuned Model"
- Type: String (description text)
- Default: Falls back to “Custom model (MODEL_ID)”
- Description: Description text for the custom model option.
- Example:
export ANTHROPIC_CUSTOM_MODEL_OPTION_DESCRIPTION="Fine-tuned on internal codebase"
- Type: String (model ID)
- Default:
haiku-4.5 (or the Haiku override)
- Description: Override the small/fast model used for internal quick operations like context compaction and summarization.
- Example:
export ANTHROPIC_SMALL_FAST_MODEL=claude-haiku-3-5
- Type: String (AWS region)
- Default: Falls back to the general Bedrock region (AWS_REGION)
- Description: Specific AWS region for the small fast model when using Bedrock. Allows routing small operations to a different region.
- Example:
export ANTHROPIC_SMALL_FAST_MODEL_AWS_REGION=us-west-2
- See also: AWS_REGION, CLAUDE_CODE_USE_BEDROCK
- Type: String (enum: “low”, “medium”, “high”)
- Default: “high”
- Description: Set the reasoning effort level for extended thinking on supported models. Affects token usage and reasoning depth.
- Example:
export CLAUDE_CODE_EFFORT_LEVEL=medium
- Type: Boolean (1, true, 0, false)
- Default: false
- Description: Force effort level support on all models, not just opus-4-6 and sonnet-4-6. Useful when using third-party models with thinking capability.
- Example:
export CLAUDE_CODE_ALWAYS_ENABLE_EFFORT=1
- Type: Integer
- Default: Unspecified (0 disables thinking)
- Description: Maximum tokens for extended thinking. If > 0, enables thinking with a fixed budget. Parsed as int; 0 or negative disables.
- Example:
export MAX_THINKING_TOKENS=8000
- Type: Integer
- Default: Model-dependent (typically 4096)
- Description: Maximum output tokens for responses. Validated against a per-model upper limit. Parsed as int.
- Example:
export CLAUDE_CODE_MAX_OUTPUT_TOKENS=8000
- Type: Integer
- Default: Unspecified
- Precedence: Only applied when DISABLE_COMPACT is set
- Description: Override the maximum context tokens. Must be > 0 when set.
- Example:
export CLAUDE_CODE_MAX_CONTEXT_TOKENS=200000
- See also: DISABLE_COMPACT, CLAUDE_CODE_AUTO_COMPACT_WINDOW
- Type: String (model ID)
- Default: Unspecified (uses normal model selection logic)
- Description: Force a specific model for all sub-agent and teammate operations, overriding normal model selection.
- Example:
export CLAUDE_CODE_SUBAGENT_MODEL=claude-sonnet-4-6
- Type: String (JSON object)
- Default: Unspecified
- Description: Extra JSON body parameters to include in API requests. Merged with standard request body.
- Example:
export CLAUDE_CODE_EXTRA_BODY='{"temperature": 0.5}'
- Type: String (JSON object)
- Default: Unspecified
- Description: Extra metadata to include in the API request metadata field. Merged with standard metadata.
- Example:
export CLAUDE_CODE_EXTRA_METADATA='{"user_id": "123", "session": "abc"}'
- Type: Boolean (1, true, 0, false)
- Default: false
- Description: Enable fallback behavior for all primary models, not just specific ones. When enabled, allows retrying with other models on failure.
- Example:
export FALLBACK_FOR_ALL_PRIMARY_MODELS=1
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