Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The readOnlyHint annotation already tells the agent this is a safe, non-mutating read, so the bar is lower. The description does add genuine value by disclosing what the document contains (attachments, attributes, relationships), but says nothing about pagination, size, error behavior, or what happens when the asset is missing.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.