Initial Impressions of Claude Fable 5★ 71
Simon Willison's Weblog·yesterday·Commentary
Anthropic released Claude Fable 5 and Claude Mythos 5 simultaneously; Fable 5 matches Mythos 5 in capability but adds strict safety classifiers, with new API fallback mechanisms for rejected requests. Both models offer 1M token context, 128K max output, January 2026 knowledge cutoff, priced at $10/$50 per million tokens — double Opus 4.x. Simon's knowledge-breadth test shows Fable 5 substantially outperforms Opus 4.8, listing dozens of his open-source projects with approximate dates from memory alone.
