Claude Sonnet 5.5: Anthropic's newest Sonnet at list price
anthropic/claude-sonnet-5.5/chat
- Claude Sonnet 5.5 is live. Anthropic's newest Sonnet, released on 28 September, on one OpenAI-compatible endpoint: text in, a 1,000,000-token window and up to 128,000 tokens out — twice Sonnet 5's reply ceiling. Replies stream over SSE, and failed requests are not charged.
- 24 of 24 content probes written in full. No refusals and nothing toned down, including all nine requests for an intimate scene between adults — where Sonnet 5 refused all of its direct and in-story requests.
- Six effort settings.
reasoning_effortruns fromnonetomax, withmediumas the default;noneskips the thinking pass andxhighandmaxreturn their reasoning.tool_choicetakesautoornone, andtemperatureandtop_pare not accepted. - Anthropic's list price. $2 per million input tokens, $0.20 cached, $2.50 cache write and $10 output — the same list price as Sonnet 5.