Initial impressions of Claude Fable 5
Anthropic releases Claude Fable 5 and Mythos 5, frontier models with 1M context at double Opus pricing.
“It's slow, expensive and has been quite happily churning through everything I've thrown at it so far.”
Anthropic launched Claude Fable 5 and Claude Mythos 5, frontier models with a 1M-token context window, 128K max output, and a January 2026 knowledge cutoff, priced at twice Opus 4.x rates. Fable 5 ships with strict safety classifiers (plus new API refusal-handling and model-fallback options) while Mythos 5 offers the same capabilities without those guardrails. The release signals Anthropic bifurcating its frontier offering along a safety-vs-unrestricted axis at a premium price point.