Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It only conveys that the operation is a read ('fetch'), but discloses nothing about behavior on missing revisions, potential errors, authentication requirements, or return format. This is minimal and does not go beyond the obvious semantics of the verb.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.