Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Beyond the read-only/idempotent annotations, it discloses return contents (dated revenue figures with label/value/as_of/source_url, growth series, related businesses), error behavior on unknown slug, and cost/rate limit (free, 100 calls/day without a key). That is exactly the operational context annotations cannot carry.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.