Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The schema has no descriptions for its two parameters, so the description must compensate. It adds purpose by saying 'your subject and message' are delivered, which clarifies that both parameters are sent. However, it does not explain expected content, formatting, or constraints beyond the schema's names and types.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.