Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the burden. It clearly indicates a read-only action ('Lists') and defines the scope ('all the Microsoft Teams the user belongs to'). However, it does not disclose prerequisites like needing an authenticated Teams connection, nor does it mention potential pagination or output format.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.