Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already signal a non-read-only, non-idempotent mutation, and the description's 'durable' adds useful context that the document persists after creation. It doesn't disclose duplicate-title handling, required permissions, or whether creation implies publication (publish_article is a separate sibling), but with a full annotation set the burden on the description is lower.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.