Anthropic released Claude Fable 5.1 and Claude Mythos 5.1. Reports from Neowin and The New Stack state the updates keep Fable's existing pricing while cutting cache read costs and overall usage. The models post gains on Terminal-Bench and apply fewer safeguard blocks that previously routed queries elsewhere. Anthropic also announced Enterprise Frontier Safeguards to support ZDR compliance for regulated sectors and introduced text watermarking that skips code tokens.