Anthropic releases Claude Fable 5.1, an upgrade to its most capable model class

Anthropic has released Claude Fable 5.1, the latest upgrade to its most capable class of models, and it is available everywhere today. The company says it handles complex, long-running, multi-step work and avoids shortcuts when fixing root causes of software issues. At lower effort levels, Fable 5.1 can match or beat Fable 5 at a much lower cost, according to Anthropic's benchmarks.