Anthropic launches Claude Fable 5.1 and Mythos 5.1, its most capable AI models yet. Fable 5.1 doubles its predecessor's score on Terminal-Bench-Science and improves agentic coding by over 30 percent. Costs drop by up to 45 percent for long, autonomous runs with many tool calls.

In June, Anthropic first released Fable 5, its Mythos-class AI model for Claude. Three months later, Anthropic is enhancing Claude...

Anthropic releases Claude Fable 5.1 broadly and Mythos 5.1 to vetted Project Glasswing users, with 1M token context and reduced cache costs.