thinking and it won’t think” no longer applies. Opus 5.5 and Fable 5.1 cannot disable thinking; Sonnet 5.5 uses between_tools; Haiku 5.5 and Opus 5 can disable it when effort is high or lower.
It also documents effort defaults (only Opus 5.5 / Haiku 5.5 default to medium; the rest default to high), the 128,000 max output, thinking tokens counting toward max_tokens, display and streaming events, common 400s, and official doc links.
The Claude rows in the reasoning-model empty-response FAQ were corrected too: the effort parameter is now output_config.effort, and budget_tokens is gone on 4.7 and newer.
📖 Claude thinking guide · 📖 Empty-response FAQ
← Back to live updates · 📚 Monthly archive