Unverified50% confidenceFactExact time
Claude Opus 5.5 cannot disable thinking: at all effort levels it rejects thinking.type set to disabled, as well as the combination of enabled + budget_tokens, and the API returns a 400 error.
1
Sources
50%
Confidence
Medium-term (~90 days)
Relevance
10/15/2026
First Seen
Valid until: 1/13/2027
Sources
Related Entities
Related Claims
UnverifiedClaude Opus 5.5's thinking process is always on and cannot be fully disabled; to save tokens, the effort level should be lowered rather than thinking turned off.67% similarUnverifiedClaude Sonnet 5.5's thinking mode cannot be turned off, forced tool calls will return an error, and non-default sampling parameters will return an error.66% similarUnverifiedOn Opus 5.5, asking Claude to write out its full reasoning process before answering may be flagged and rejected, with the error reason shown as 'reasoning extraction,' intended to prevent other companies from distilling Opus 5.5.63% similar
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