The trick: Zero Underneath
Anthropic will watermark Claude's text.
Anthropic also says paraphrasing removes it.
every Claude model launched on or after August 2 now weaves an invisible, machine-readable watermark into the text it writes, so AI content can be detected.
Before you read on. Your call?
TRUE, BUT
0 accuracy rates
read Anthropic's own help page. The mark may vanish if the text is 'heavily edited, paraphrased, translated, or mixed into other writing', or if the passage is short. There are zero published detection-accuracy or false-positive numbers, and the third-party detector is 'forthcoming'.
The twist
the mark only shows Claude 'had a hand' in something, not that Claude wrote it. So it cannot clear a human who used Claude lightly, and it cannot catch a cheat who runs one paraphrase pass. It is real, it is default, and it solves the easy half of the problem while the hard half strips it in one step.
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The trick has a name
We call it Zero Underneath: the headline number has nothing behind it. You'll see it again. Learn to spot it →
Receipts
- Context support.claude.com:
The text has been heavily edited, paraphrased, translated, or mixed into other writing
- Refutes fortune.com:
Anyone determined to disguise AI output has plenty of ways to degrade or erase a statistical text watermark.
- Supports techcrunch.com:
it will travel with the text when it's copied and pasted elsewhere, and may persist through some editing
- Context fortune.com:
The new detection mark only shows Claude had a hand in something, not that a Claude model generated the entire thing.
Open the Receipts Pack → What each source proves, every figure traced, and what would change our verdict.