Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the transparency burden, and the imperative 'Read this' plus a provenance lookup implies a safe, non-mutating operation. It also discloses the returned information, though it does not explicitly state permissions, side effects, or response format.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.