Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover readOnly, idempotent, openWorld and non-destructive, and the description adds real data-quality context beyond them: EPS is not normalized, past estimate revisions are unavailable, missing source rows are reported rather than filled, and selected metric trends are distinct from the full statement JSON. It stops short of stating response size, latency, or auth requirements.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.