Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already indicate idempotence and non-destructive behavior. The description adds meaningful behavioral specifics not in the schema or annotations: the created room is empty, private, investor uploads are disabled, and a stable idempotency key is required. It does not cover error or output behavior, but the output schema and annotations reduce that burden.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.