Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the burden of conveying behavior. 'Read this' implies a read-only, non-destructive operation, and the listed content (source, date, licence, citation) describes what the agent can expect. It does not discuss edge cases or return formatting, but for a simple metadata endpoint this is adequate.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.