Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare the operation as read-only, idempotent, open-world, and non-destructive. The description adds useful behavioral details beyond annotations: the -1 fallback when no greater element exists and the 1-credit cost. It does not cover edge cases such as duplicates or empty input, so it stops short of a 5.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.