Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover readOnly, idempotent, openWorld, and non-destructive behavior. The description adds meaningful context beyond those: the data source (GRACE groundwater trend), the two-tier behavior, and the 'non-locating' property of the authenticated atlas indication. This gives the agent useful behavioral expectations without contradicting annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.