You'll noticeTier: how much it should matter to you
3Useful: my rating, 1 to 5
2Signal: worth watching, 1 to 5
PermissionsArea: what it touches
ImprovementsKind: in v2.1.280,
ImprovementsSection of the release
What
When a message is flagged by Anthropic's safety systems and the model in use is claude-opus-5-5, Claude Code now shows tailored explanatory text instead of the older generic message. The new text has separate wording for cyber-related, biological, and general "frontier model" categories, and notes that this may be the first time a user encounters such a flag on an Opus model.
Why
This gives users flagged on Opus 5.5 a clearer, more specific explanation of why their message was refused or answered by a fallback model, rather than a generic notice.
How sure we are
One source agreesOne thing we can check says the same as this entry.
Anthropic's release notes agreeAdded Claude Opus 5.5 (claude-opus-5-5), now the default Opus model — 1M context, $4/$20 per Mtok with $0.20/Mtok cache reads
