Server provides 2 tools with basic parameter schemas and descriptions. Both tools have input schemas visible in code (Zod definitions), but descriptions are minimal (12-38 chars, below ideal 50-200 char range). Output structure is undocumented, responses are plain text wrapped in MCP content arrays with no return type schema. Error handling is present but minimal: divide-by-zero returns a text message rather than structured error guidance. No parameter validation documentation (e.g., numeric ranges, operation constraints). Tool naming is clear and verb-based (add, calculate), but descriptions fail to explain WHEN to use each tool or what distinguishes them. The 'calculate' tool has an enum constraint (operation field), which is correct, but parameter descriptions are generic ('First operand' rather than contextual guidance).

• Expand tool descriptions to 50-200 chars. Example: 'add: Performs simple addition of two numbers. Use this for basic two-operand addition. For operations beyond addition (subtract, multiply, divide), use the calculate tool instead.' This clarifies intent and distinguishes from calculate.
• Document return types explicitly. Add to tool metadata: 'Returns: {content: [{type: "text", text: string}]} where text contains the numeric result as a string.' Or define a structured output schema (e.g., {result: number, operation: string}).
• Improve error messages to guide agent recovery. Change divide-by-zero response to: 'Error: Cannot divide by zero. Parameter b must be non-zero. Please provide a non-zero divisor for the second operand.' Include the parameter name and valid constraint.
• Add constraint documentation to numeric parameters. Example: 'a: number, A valid numeric operand (integers or decimals). No specific range limits; behavior at extremes (Infinity, -Infinity, NaN) will return an error.' This sets expectations for invalid inputs.
• Consider consolidating 'add' and 'calculate' into a single tool with operation enum, or clearly document when to prefer each. If keeping both, add to 'add' description: 'For multi-operation support, use the calculate tool.' and to 'calculate': 'For simple addition only, consider using the add tool for cleaner agent planning.'
• Implement structured error responses using MCP error protocol (if available in SDK). Replace text-based errors with: {error: {code: 'INVALID_INPUT', message: '...', context: {parameter: 'b', constraint: 'non-zero'}}}.