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Company also changes data retention policy.
Key facts
Fable 5 and Mythos 5 both charge $10 per million input tokens and $50 per million output tokens, which is less than half the price of Claude Mythos Preview ($25/m input, $125/m output)
The AI biz on Tuesday announced public availability of Claude Fable 5, a Mythos-class model, and private availability of Claude Mythos 5 for Glasswing partners
Mythos 5 delivers the strongest results yet for resisting prompt injection attacks, which saw a success rate of 4.8 percent over 100 attempts, per the model safety card [PDF]
In terms of benchmarks, the two models significantly outperform Anthropic's own Opus 4.8, OpenAI's Codex 5.5, and Google's Gemini 3.1 Pro on the chosen test suite
Summary
The AI biz on Tuesday announced public availability of Claude Fable 5, a Mythos-class model, and private availability of Claude Mythos 5 for Glasswing partners. "Fable 5’s capabilities exceed those of any model we’ve ever made generally available," the company said. As if to suggest that the current technocracy still has room for humanities scholars, Anthropic notes that the name Fable comes from the Latin fabula, "that which is told," similar to the Greek mythos. "The safeguards are what distinguish the two models (Fable and Mythos) and are why we’ve given them different names," the company said. Anthropic considers Fable capable of causing serious damage without safeguards.