Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is clear. The description adds behavioral context by stating it returns 'available' slots and describing the output content (name, type, floor price, pricing models, capacity, geo targets, status). It also notes filtering by publisher_id, slot_type, pricing_model, or geo, which goes beyond 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.