Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the burden of disclosing behavior. It does disclose that classification is AI-based, that labels default to spam/urgent/technical/finance/general, and that the return value is the best single label. However, it does not describe output format, edge-case behavior, latency, external AI dependencies, or data handling, which are relevant for an unannotated AI tool.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.