Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description must convey behavioral traits. 'List all work packages' clearly implies a read-only operation and the scope is specified. However, it doesn't disclose potential details like pagination, ordering, or permission requirements, which are not critical for a simple list but could be relevant.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.