Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the burden of disclosure. It adds non-obvious details: it retrieves from the user's Drive and orders by last modified date. This provides meaningful context beyond the tool name, though it doesn't mention pagination or that it is read-only, which is implied by 'Retrieves'.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.