Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and idempotentHint=true, so the agent knows this is a safe, repeatable read operation. The description adds minimal behavioral context by specifying the date/date range scope, but doesn't disclose other traits like rate limits, authentication needs, or what specific exercise data is returned. With annotations covering safety, a 3 is appropriate as the description adds some value but not rich behavioral details.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.