Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%, so the baseline is 3. The description adds value beyond the schema by clarifying that guideSlug accepts 'a close approximation of its title', not just the canonical reference, which helps an agent pass user phrasing directly. The other params remain fully documented in the schema.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.