Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=true, and destructiveHint=false, fully disclosing the safety profile. The description adds value by specifying the exact return fields and the 'full' nature of the entry, plus the numeric ID constraint, going beyond the bare annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.