Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations and no output schema, the description carries the full burden, and it does disclose the exact contents an agent will receive: source, compute date, licence and citation. It stops short of stating read-only/safety characteristics or the citation format, but for a static metadata lookup the disclosure is solid.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.