Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare the tool read-only, idempotent, and non-destructive, so the description builds on that rather than repeating it. It discloses important behavioral details not visible from annotations: websearch query semantics, AND/OR/exclusion behavior, quoted phrase matching, truncation of descriptions, capping of extracted products, and the pointer to get_product_recall for full text.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.