Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare the tool as read-only and closed-world, and the description adds meaningful context about the underlying algorithm (precomputed simGIC) and how similarity is explainable (number of shared phenotypes). This goes beyond what annotations provide and helps set expectations about the kind of results, though it does not mention any rate limits, pagination, or result ordering.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.