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.

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.

Source: TechMeme
Source Link: https://www.techmeme.com/260901/p48#a260901p48