Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=true, so safety and network profile are covered. The description adds that data comes from a public endpoint and is 'normalized', which is mild extra context, but it says nothing about pagination behavior, rate limits, or what happens with invalid URLs beyond what the schema states.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.