Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The annotations already declare read-only, idempotent, and non-destructive behavior, lowering the bar. The description adds that this is a prerequisite and provides metadata for querying, offering useful context beyond the annotations without contradicting them.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.