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 conversational behavior (answer on behalf when possible), the response status handling ('complete' → get_answer), and the authentication fallback mechanism (leave api_key blank unless connector can't send headers). This is rich behavioral context.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.