Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint and idempotentHint, so the agent knows it's safe and idempotent. The description adds that it returns usage counts, which is helpful context beyond annotations. However, it does not disclose potential performance implications or output size, which could be relevant for large datasets.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.