Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The input schema already provides a comprehensive description of the 'expression' parameter, covering operators, symbols, variables, constants, and limits (100% coverage). The description adds some context about parsing and output, but doesn't introduce new parameter-specific semantics beyond what the schema already states. Thus, the baseline score of 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.