Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations provide readOnlyHint=true, destructiveHint=false, idempotentHint=true, and openWorldHint=true, covering safety and idempotency. The description adds no behavioral context beyond this, such as rate limits, authentication needs, or what 'getAll' entails (e.g., pagination, sorting). Since annotations are comprehensive, the bar is lower, but the description does not enhance understanding beyond the structured data.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.