Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations present, the description bears full responsibility for behavioral disclosure. It only states that the tool retrieves messages, with no mention of read-only nature, authentication, rate limits, data freshness, or response characteristics. This is insufficient for safe invocation.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.