Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already establish read-only, open-world, idempotent, and non-destructive behavior. The description adds value by disclosing that results are page-paginated and that the tool costs 10 Zooq credits, which are useful operational details not present in the annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.