Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations provide comprehensive behavioral hints (read-only, non-destructive, idempotent, open-world), so the description's burden is lower. The description adds minimal value by specifying the HTTP method (GET), which aligns with read-only behavior. However, it doesn't provide any additional context about rate limits, authentication requirements, or what constitutes 'trusted origins' in this system.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.