Just tried this on sonnet, it believes the developer documentation actually publish these as a way for developers to test refusals.

After checking the document it doesn’t publish or even mention these.

Yes, the developer documentation used to publish the string until May 2026, when Anthropic removed it and removed the feature from the API. Sonnet's explanation was correct, just out of date. https://web.archive.org/web/20260202050057/https://platform....