News · curated 25 Jul 2026
Quoting Boris Cherny
First reported simonwillison.net
Coverage timeline
Single-source analysis — first reported, latest, and curated coincide.
Why it matters
Prompt injection robustness of deployed agentic models like Claude Opus 5 directly affects the attack surface defenders must reason about when deploying AI agents and copilots.
A quotation from Anthropic's Boris Cherny, collected by Simon Willison, highlights that Claude Opus 5 is described in its system card as Anthropic's 'least prompt injectable model yet,' with the card reporting the largest agentic-safety gains in prompt injection robustness across coding, computer use, and browser use.