Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, closed-world, so the safety profile is covered; the description still adds real context beyond them — corpus size (86 pages), index freshness date, hybrid keyword/semantic ranking, and per-result short snippets. The paging contract (offset + limit arithmetic on hasMore) is genuinely behavioral detail not present in the annotations. It falls short of a 5 only because it says nothing about ranking quality or truncation beyond snippets.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.