Fable 5.1 is now generally available, while Mythos 5.1 is only available through Anthropic’s “trusted access” programmes.

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.