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Sweep 22 Oct 2026 · 04:32Z Build v2.1.308 527 read Stable v2.1.308 Latest v2.1.308 Next v2.1.308 Feeds RSS JSON llms.txt llms-full.txt Unofficial
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Claude Code v2.1.248 ·

Reasoning effort levels and their aliases

Reasoning effort accepts low through max, with med and ultracode as aliases.

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What

Reasoning effort accepts low, medium, high, xhigh and max, with med accepted as an alias for medium and ultracode as an alias for xhigh.

Details
  • A related state object gained unusableWritingOverrideTold, defaulting to false, tracking whether a one-time notice has been shown.
Evidence

["low", "medium", "high", "xhigh", "max"]

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Read from
Names in the bundlelowmediumhighxhighmax
Since it was published

The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.

Confirmed since Anthropic's documentation has since written up medium, on Create Session. - `effort: optional "low" or "medium" or "high" or 2 more or BetaManagedAgentsEffortLow or BetaManagedAgentsEffortMedium or 3 more or null` api/beta/sessions/create see the edit
Confirmed since Anthropic's documentation has since written up max, on Model configuration. Frontmatter effort applies when that skill or subagent is active, overriding the session level but not the environment variable. A [`maxEffortLevel`](/docs/en/settings-reference#maxeffortlevel) or [organization effort cap](#organization-ef… model-config see the edit
Confirmed since Anthropic's documentation has since written up high, on Model configuration. * The model doesn't support `xhigh` effort model-config see the edit
Confirmed since Anthropic's documentation has since written up xhigh, on Model configuration. * The model doesn't support `xhigh` effort model-config see the edit
Added since A small documentation edit on CLI reference touched a line naming max after this was published. | `--effort` | Set the [effort level](/docs/en/model-config#adjust-effort-level) for the current session. Options: `low`, `medium`, `high`, `xhigh`, `max`, or `ultracode`. Available levels depend on the model. `ultracode` requests `xhigh` … cli-reference see the edit
Added since A small documentation edit on CLI reference touched a line naming medium after this was published. | `--effort` | Set the [effort level](/docs/en/model-config#adjust-effort-level) for the current session. Options: `low`, `medium`, `high`, `xhigh`, `max`, or `ultracode`. Available levels depend on the model. `ultracode` requests `xhigh` … cli-reference see the edit
How sure we are
One source agreesOne thing we can check says the same as this entry.
Anthropic's documentation agreesAnthropic's documentation has since written up low, on Give Claude access to your tools.

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