fable

Anthropic released Fable, a public version of its cybersecurity model Mythos, but security researchers report the model's guardrails are blocking routine tasks. The model flags requests as cybersecurity-related even for reading blog posts or requesting code reviews, downgrading to Claude Opus 4.8 when triggered.

Anthropic has released Claude Fable 5, its first publicly available Mythos-class model, at $10 per million input tokens and $50 per million output tokens—less than half the price of Claude Mythos Preview. The model includes safeguards that redirect sensitive queries to Claude Opus 4.8 in less than 5% of sessions.

Anthropic has released Claude Fable 5, marking the first broad release from its Mythos class of AI models. The company previously deemed this model family too dangerous for public release due to exceptional cybersecurity capabilities, but new safeguards that block responses in high-risk areas now make it available at $10 per million input tokens and $50 per million output tokens.