Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries full burden for behavioral disclosure. 'Read data' implies a read-only operation, but it doesn't specify what 'data' means (values, formulas, formatting?), whether authentication is needed, if there are rate limits, what happens if the worksheet doesn't exist, or what format the returned data takes. This leaves significant behavioral questions unanswered.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.