Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It says 'Check if...' which implies a read-only operation, but it does not disclose whether this is a local check, whether it makes network calls, or what happens if the token is missing—leaving the agent uncertain about side effects and behavior.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.