Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is fully covered. The description adds value by disclosing the non-obvious ordering caveat (catalog-based, not epoch-based) and its approximation quality. It doesn't discuss pagination, rate limits, or result format beyond what the output schema would provide.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.