Introducing Claude Opus 5.5, the first model in our new Claude 5.5 family

Claude Opus 5.5, the first model in the new Claude 5.5 family, is now available. It performs at the level of Claude Fable 5.1 for most tasks but costs 40% less to run than Opus 5. Opus 5.5 outperforms both Opus 5 and Fable 5.1 on nearly every benchmark, excelling in agentic coding and real-world knowledge work. It is also more efficient, using fewer tokens per task at a lower price, and generates output over 30% faster than Opus 5. Additionally, it communicates more naturally, addressing common feedback from Opus 5.

This is the first release since the company called for pacing frontier models, with external evaluators testing it before release.