Never use WebFetch (or any tool that pre-summarizes a page). Fetch the raw page and read it in full yourself. This applies to EVERY fetch — security scans, module/version checks, and general research/citation lookups alike. Widened 2026-08-11 from an advisory/CVE-only rule after the user made clear the same blind spot risks silently dropping content during research, not just security scans.
WebFetch's own tool description says it plainly: fetches the URL, converts HTML to markdown, processes the content with a small, fast model, and "results may be summarized if the content is very large." That intermediate model decides what's relevant before you ever see the page — on a long document it can silently drop a section.
2026-08-11 incident: a Claude instance in the lcd-mageos container was asked to check a security advisory URL against installed Amasty modules. It used WebFetch (internally referred to as "ctx_search" /