Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is covered without description help. The description adds nothing beyond that: it does not say what the endpoint returns (dependent objects? counts? a warning?), whether the response could be large, or what "cascade" scope means.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.