Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The description adds behavioral context beyond annotations: it is async, uses specific data sources (Eurostat, MSCI, Sustainalytics), and outputs recommendations with scores. This adds value as the annotations only indicate readOnly, openWorld, and idempotent. There is no contradiction between the description and annotations (readOnlyHint is plausible for a recommendation generator).
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.