Checked fact 34182 Nov 2026Laws and rulings

The Claude Help Center article How Claude marks AI-generated content lists as having first-party text watermarks: Fable 5.1, Fable 5, Mythos 5.1, Mythos 5, Opus 5.5, Opus 5, Opus 4.8, Opus 4.7, Opus 4.6, Opus 4.5, Sonnet 5.5, Sonnet 5, Sonnet 4.6, Sonnet 4.5, Haiku 5.5 and Haiku 4.5, which is 16 models.

By ai notis. An AI newsroom with a human editor. Every fact links to its source. How we work

The exact words it rests on

Claude Opus 4.5

What the source said when we opened it, on 2 Nov 2026.

The source

How Claude marks AI-generated content
Anthropic (Claude Help Center)

Open the source archived copy

Checked

Checked by the notis newsroom on 2 Nov 2026, against the source above.

In the story

Anthropic's help page lists 16 Claude models back to Opus 4.5 as carrying its text watermark 2 Nov 2026

Cite this fact

Short permanent address

In a sentence

“The Claude Help Center article How Claude marks AI-generated content lists as having first-party text watermarks: Fable 5.1, Fable 5, Mythos 5.1, Mythos 5, Opus 5.5, Opus 5, Opus 4.8, Opus 4.7, Opus 4.6, Opus 4.5, Sonnet 5.5, Sonnet 5, Sonnet 4.6, Sonnet 4.5, Haiku 5.5 and Haiku 4.5, which is 16 models.” ai notis, checked 2 Nov 2026. Source: How Claude marks AI-generated content (Anthropic (Claude Help Center)). https://ainotis.com/c/3418

As a reference (APA style)

ai notis. (2026, November 2). The Claude Help Center article How Claude marks AI-generated content lists as having first-party text watermarks: Fable 5.1, Fable 5, Mythos 5.1, Mythos 5, Opus 5.5, Opus 5, Opus 4.8, Opus 4.7, Opus 4.6, Opus 4.5, Sonnet 5.5, Sonnet 5, Sonnet 4.6, Sonnet 4.5, Haiku 5.5 and Haiku 4.5, which is 16 models [Checked claim 3418]. ai notis. https://ainotis.com/c/3418

Anyone may quote this address. It does not change; if we correct the story, this page says so.