Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already establish read-only, idempotent, non-destructive, closed-world behavior, so the bar is lower. The description still adds real context: the exact scope of the payload, the 7-day window, the 12-price cap, and the reassurance that no patient or clinical data is returned.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.