Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover read-only, idempotent and open-world behavior, so the lower bar applies. The description adds real semantic context beyond that: what the response contains (ranks, ties, USD revenue, confidence, sources) and the warning that revenue, ARR, run-rate and forecasts carry distinct basis labels, which prevents an agent from conflating metrics.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.