Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover readOnly, idempotent, non-destructive, and open-world behavior, so the bar is lower. The description adds meaningful behavioral context by explaining the draft-versus-version config behavior and instructing the agent to follow llmContext guidance in results, which is beyond what annotations provide.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.