Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. Beyond that the description adds only the profile scoping; it says nothing about the api_key parameter's role, whether the key is per-call or ambient, or what the account objects contain, which matters for a tool flagged openWorld.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.