Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare read-only, idempotent, and non-destructive behavior, so the baseline is satisfied. The description adds valuable behavioral context by explaining what metrics are computed (value vs. cost, trend, success rate, pre-AI baseline) and that it is an analysis rather than a mutation. It does not contradict annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.