Anthropic is adding its word-choice watermark to Claude Mythos 5, Opus 4.7, Opus 4.6 and Sonnet 4.6, citing the EU AI Act's December deadline. It says the watermark adds no tokens and does not change meaning or quality. On Opus 4.6 and Sonnet 4.6, The Decoder reports it applies only while temperature, top_p and top_k stay at their defaults, so teams passing custom sampling settings may avoid it. The rollout on Amazon Bedrock may take a few extra days.
