Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Given that annotations already declare readOnlyHint=true and destructiveHint=false, the description adds value by detailing what the comparison covers: roast, body/acidity/sweetness, shared vs distinct flavors, brew methods, and price difference. This goes beyond the annotations to set expectations about the content returned.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.