This is a simple calculator MCP with 2 tools. Both tools have explicit schemas with type definitions and enum constraints (good), but descriptions are extremely terse (12-45 chars) and lack context for LLM selection. The 'calculate' tool has a solid enum-based operation parameter, but no tool provides guidance on when to use it vs alternatives, error conditions, or output format. Parameter descriptions are present but minimal. No error handling guidance is provided, divide-by-zero returns text instead of a structured error. Overall, this is a functional but barebone implementation lacking production-grade documentation. Naming is adequate (verb-based: 'add', 'calculate'), but descriptions fall well below the 50-200 char baseline for A-grade tools.

• Expand tool descriptions to 50-150 characters, explaining WHAT the tool does, WHEN to use it, and WHAT it returns. Example: 'Adds two numbers together. Use this for basic arithmetic. Returns the numeric sum as a string.'
• For 'calculate', clarify when to use it vs 'add': 'Performs arithmetic with multiple operation types (add, subtract, multiply, divide). Use when operation type is not known in advance. Returns result as a string; divide-by-zero returns error text.'
• Add numeric constraints to parameter descriptions: 'First number (any real number, positive or negative; supports decimals)' instead of just 'First number'.
• Implement structured error handling: return error objects with code/message/recovery guidance instead of plain text. Example: {error: {code: 'DIVIDE_BY_ZERO', message: 'Cannot divide by zero', recovery: 'Choose non-zero divisor'}}
• Document output schema in tool descriptions or separately. Example: 'Returns: {content: [{type: "text", text: "<numeric result as string>"}]}'
• Consider splitting 'calculate' into operation-specific tools (add, subtract, multiply, divide) if they are called independently, or keep 'calculate' as the composition layer and note that 'add' is a convenience alias.