Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, and destructiveHint. The description adds valuable behavioral context by clarifying that ranking is based on real units sold from captured orders, which prevents the agent from treating 'most popular' as a subjective or review-based measure.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.