Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, openWorld, idempotent, and non-destructive behavior. The description adds that it returns the conversion rate and that the rate is 'current', providing a bit of behavioral context. However, it does not elaborate on data source, rate freshness guarantees, or other limitations, so it adds limited value beyond the annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.