Model Releases
Claude Fable 5.1 and Mythos 5.1 are Anthropic's first models to watermark text outputs; a detection API is available to eligible groups as required under EU law (Ben Patterson/PCWorld)
Ben Patterson / PCWorld: Claude Fable 5.1 and Mythos 5.1 are Anthropic's first models to watermark text outputs; a detection API is available to eligible groups as required under EU law — Aside from b
Ben Patterson / PCWorld: Claude Fable 5.1 and Mythos 5.1 are Anthropic's first models to watermark text outputs; a detection API is available to eligible groups as required under EU law — Aside from being more powerful than their predecessors, Claude Fable 5.1 and Mythos 5.1 will add invisible watermarks all their text and file outputs.
Related
- Anthropic details Claude's text watermark: it only shows Claude was likely involved, is sparse in code and factual text, and disappears after a full rewrite (Anthropic)
- Anthropic's text watermark alters word probabilities to embed a fingerprint, which could degrade Claude's writing, despite its claim of no impact on quality (John Gruber/Daring Fireball)
- Anthropic says new Claude models in the EU will add watermarks to text and C2PA metadata to files, to comply with the EU AI Act, and it will update older models (Thomas Claburn/The Register)
Source: Techmeme | 2026-09-01