Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already indicate read-only, idempotent, and non-destructive behavior. The description adds useful behavioral context: only released scores are included, teacher rosters and answer keys are not exposed, and completing work is not possible through this tool. This clarifies limits beyond the structured annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.