Claude Fable 5
Anthropic · 2026-06-09
Claude Fable 5 and Claude Mythos 5 are deployments of Anthropic's June 2026 checkpoint with identical model weights. The default Fable 5 deployment is generally available with external production safeguards; Mythos 5 is offered through trusted access programs under a different safeguard policy. Safeguard interventions and fallback to Opus 4.8 can change observed results and depend on the deployment and evaluation configuration.