
Anthropic releases Claude Fable 5.1 and Mythos 5.1
Fable 5.1 scores 55.8% on Terminal-Bench 4.0 in Claude Code, ahead of Fable 5 (42%) and Opus 5 (52.3%). Pricing matches Fable 5, but API cache reads drop 75% to $0.25/MTok; Perplexity ranked it first on its August WANDR eval at 0.601.

