Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the behavioral burden. It frames the tool as a read operation ('Read this') and lists exactly what information will be provided, implying no side effects. It does not discuss output formatting or access prerequisites, but for a zero-parameter provenance lookup these are minor.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.