Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover the safety profile (read-only, non-destructive, not open-world), so the description does not need to repeat that. It adds useful behavioral context by stating that results contain page IDs, titles, URLs and excerpts rather than full content, and it signals that full content requires a separate call.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.