Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are supplied, so the description carries the burden; it does so by disclosing the four categories of information the call returns (source, computed date, licence, citation). It doesn't explicitly state that the operation is non-mutating, but it enumerates output content that would otherwise be unknown, which is meaningful added context for a zero-annotation tool.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.