Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries full responsibility for disclosing side effects. It only states the action without mentioning potential errors (e.g., no active session), data saving, or state changes, leaving the agent underinformed about consequences.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.