Anthropic launches Claude Fable 5.1 and Mythos 5.1

Anthropic released Claude Fable 5.1 and Mythos 5.1, cutting cache read prices from $1 to $0.25 per million tokens. Fable 5.1 scores 52.6% on Terminal-Bench-Science 0.1, more than double Fable 5's 24.7%. Both models include built-in watermarks required by the EU AI Act.