Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description must carry the transparency burden. 'List' communicates a read-only, non-destructive operation, and 'registered to this account' clarifies scope. It does not disclose whether the data is live or cached, or whether an active connection is required, but for a simple listing tool this is a reasonable baseline.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.