Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly and idempotent, and the description adds useful behavioral details: it mentions the tool returns null for unresolvable slugs and lists the types of information (full description, launch date, revenue signals, for-sale status). This goes beyond the annotations without contradicting them.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.