Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world, so the safety profile is covered. The description adds a useful grounding constraint (use returned content, don't invent unsupported information) but says nothing about result quality, empty-result behavior, or match semantics. The output schema covers return values.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.