Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint false, but the description adds valuable context beyond annotations: it returns doc SETS, not content, and clarifies the exact boundary of lookup. This behavior is not redundant with the annotations and helps the agent anticipate the tool's output scope.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.