Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden of behavioral disclosure, but it only says 'Update' and the PUT endpoint. It does not state whether fields are replaced or merged, what permissions are required, what happens on invalid IDs, or what response is returned. This is thin for a mutating operation.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.