Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description adds behavioral context: 'bearer-owned' and 'never moves money' disclose that it's tied to the authenticated user and has no financial side effects. However, it does not disclose other behaviors such as session creation, expiration, or error conditions, leaving gaps.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.