Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It discloses the tool's role and provides an example of the input/output transformation, but it does not state the exact return format (e.g., a list of suggestions, corrected email only, or behavior when no typo is found). This is a gap for agent invocation.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.