Claude Opus 5.5

Anthropic has introduced Claude Opus 5.5, the first model in its new Claude 5.5 family. This model performs at the level of Claude Fable 5.1 for most tasks but costs 40% less to operate than Opus 5. It demonstrates strong capabilities in agentic coding, knowledge work, business workflows, and multidisciplinary reasoning. Notably, Walleye Capital found Opus 5.5 largely solved their evaluation suite, even identifying and correcting an error in their instructions that no other model had caught.