The whole hunk
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544544You can change effort through any of the following:
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546* **`/effort`**: run `/effort` with no arguments to open an interactive slider, `/effort` followed by a level name to set it directly, or `/effort auto` to reset to the model default
546* **`/effort`**: run `/effort` with no arguments to open an interactive slider, `/effort` followed by a level name to set it directly, or `/effort auto` to reset to the model default. You can run it while Claude is working, and once you confirm the [cache warning](/docs/en/prompt-caching#changing-effort-level), if Claude Code shows one, Claude Code applies the new level to the next request in the turn
547547* **In `/model`**: use left/right arrow keys to adjust the effort slider when selecting a model
548548* **`--effort` flag**: pass a level name to set it for a single session when launching Claude Code
549549* **Environment variable**: set `CLAUDE_CODE_EFFORT_LEVEL` to a level name or `auto`
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568568### Extended thinking
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570Extended thinking is the reasoning Claude emits before responding. On models that support [adaptive reasoning](#adjust-effort-level), the effort level is the primary control for how much thinking happens; the settings below turn thinking on or off and control how it displays.
570Extended thinking is the reasoning Claude emits before responding. On models that support [adaptive reasoning](#adjust-effort-level), the effort level is the primary control for how much thinking happens; the settings below turn thinking on or off and control how it displays. With thinking turned off on the Anthropic API, Claude Code sends effort `high` instead of a higher level to models it knows [don't accept that combination](/docs/en/errors#effort-isnt-available-with-thinking-turned-off), such as Opus 5.
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572| Control | How to set it |
573| :----------------------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
574| Toggle for the current session | Press `Option+T` on macOS or `Alt+T` on Windows and Linux |
575| Set the global default | Run `/config` and toggle thinking mode. Saved as `alwaysThinkingEnabled` in `~/.claude/settings.json` |
576| Disable regardless of effort | Set [`MAX_THINKING_TOKENS=0`](/docs/en/env-vars), which turns thinking off on the Anthropic API except on Fable 5. On [third-party providers](/docs/en/third-party-integrations) this omits the `thinking` parameter instead, and adaptive-reasoning models may still think. Other values apply only with a [fixed thinking budget](#adaptive-reasoning-and-fixed-thinking-budgets) |
572| Control | How to set it |
573| :-------------------------------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
574| Toggle for the current session | Press `Option+T` on macOS or `Alt+T` on Windows and Linux |
575| Set the global default | Run `/config` and toggle thinking mode. Saved as `alwaysThinkingEnabled` in `~/.claude/settings.json` |
576| Disable through an environment variable | Set [`MAX_THINKING_TOKENS=0`](/docs/en/env-vars), which turns thinking off on the Anthropic API except on Fable 5. On [third-party providers](/docs/en/third-party-integrations) this omits the `thinking` parameter instead, and adaptive-reasoning models may still think. Other values apply only with a [fixed thinking budget](#adaptive-reasoning-and-fixed-thinking-budgets) |
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578578Thinking cannot be turned off on Fable 5. The session toggle, `alwaysThinkingEnabled`, and `MAX_THINKING_TOKENS=0` have no effect there, and Fable 5 decides per step how much to think based on the effort level.
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