Blog & Articles Claude Fable 5: Why Anthropic Put Its Most Powerful AI Behind Guardrails by Rebecca Sutton June 9, 2026 by Rebecca Sutton June 9, 2026 TLDR Anthropic released Claude Fable 5 on 9 June 2026. It is the first publicly available Mythos-class model. Queries touching cybersecurity, biology, chemistry or model distillation get rerouted to the … FacebookTwitterLinkedinEmail