Anthropic launches Claude Fable 5.1 and Mythos 5.1, cache reads drop to $0.25/MTok

Anthropic 发布 Claude Fable 5.1 与 Claude Mythos 5.1

Anthropic released Claude Fable 5.1 (successor to Fable 5 for long-running coding and research) and Mythos 5.1 (Project Glasswing only). Both default to 1M context, 128k max output, and the same $10/$50 per MTok pricing as Fable 5. The standout change: cache reads are now $0.25/MTok—2.5% of base input price, far cheaper than other models. tool_choice drops 'any' and 'tool' modes; thinking blocks only work with same-gen or newer models; text watermarking and C2PA credentials are on by default. The post doesn't include benchmark scores or performance comparisons.

Why it matters: Anthropic dropped two new models on the same day — a substantive product update. Fable 5.1 targets long coding and research sessions; Mythos 5.1's gated release adds intrigue. 1M context, 128K output, same price — high info density. The post doesn't detail Mythos 5.1's capabil...