Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 67% across 9 parameters, so the schema already documents the subtle ones (token, note, revision, agentName/agentModel). The description adds meaning only for decisionId (idempotency), which the schema also states, and names the two verdict values already in the enum. It does not compensate for the undocumented remainder, so baseline 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.