Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint and idempotentHint, so the safety profile is covered. The description adds meaningful behavioral context: it states the output includes per-year/per-theme cuts, extremes, open book, combined closed+open buckets, and explicitly frames the tool as signal data, not investment advice.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.