Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden. 'List all' conveys a read-only, non-mutating operation and the 'all' scopes the result, but the description does not state pagination, ordering, authentication, or response shape. This is acceptable for a trivial no-parameter list but still leaves behavioral details to inference.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.