Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare the full safety profile (readOnly, idempotent, non-destructive, closed-world), lowering the burden. The description adds that the question ref must be exact, which hints at matching behavior, but says nothing about pagination (limit default 30, max 50) or how filter interacts with the base query.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.