Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the burden of behavioral disclosure. It states the tool is 'deterministic' and lists return items, which implies consistency, but it does not mention side effects, authentication needs, rate limits, or other behavioral constraints. The output schema will detail return structure, so the description provides adequate but not exhaustive transparency.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.