Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden, and it discloses the returned content but not the behavioral profile: it never states that the call is read-only with no side effects, whether authentication or licence acceptance is required, or how the citation is formatted. For a zero-parameter lookup the risk is low, so this is adequate but not rich.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.