Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already mark the tool as read-only and non-destructive. The description adds useful behavioral context beyond the annotations by specifying the contents of the catalog (slugs, EV flag, price multiplier) and confirming it returns the full supported set rather than a filtered subset.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.