25th July 2026

More than any of these eval scores, what is most exciting to me is something else: Opus 5 is our least prompt injectable model yet. It is a bit buried in the system card, but across PI evals and red teaming, Opus 5 is very hard to prompt inject successfully.

Boris Cherny, here's that System Card section, page 73

Posted 25th July 2026 at 12:42 am

Recent articles

This is a quotation collected by Simon Willison, posted on 25th July 2026.

ai 2,142 prompt-injection 157 generative-ai 1,894 llms 1,861 anthropic 315 claude 294 boris-cherny 3