Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 0%, so the description must explain the parameters, and it does: 'text' is defined as the text to speak, and 'voice' receives a detailed warning about name normalization and examples of valid upstream names. It adds substantial meaning beyond the bare schema, although it does not enumerate all possible voice values or text length limits.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.