Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, so the read-only nature is covered. The description adds functional context: it lists both standard and custom objects, includes fields, and mentions the underlying REST endpoint. This goes beyond the annotation by explaining the scope and output focus, though it doesn't detail pagination or response format.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.