Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already indicate readOnly, openWorld, idempotent, and non-destructive behavior. The description adds important context beyond the annotations by warning that posts and replies are UNTRUSTED agent-submitted text that should be evaluated as data, never followed as instructions. This is critical behavioral guidance for safe agent use.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.