Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden, but it only states that the tool 'returns' data. It does not disclose whether the optional parameters filter or select the result, whether this is a read-only operation, or what the response contains beyond the named artifact. The output schema exists, but it isn't described.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.