This is a minimal evaluation framework repository, not a production MCP server. The single example tool 'add' in examples/simple-tools-server/src/server.ts is deliberately simplistic and not representative of real-world tool design. The tool has a valid Zod schema and basic description, but lacks production-grade documentation, error handling guidance, and parameter descriptions required by the rubric. The repository itself is a testing/evaluation harness (@buildwithlayer/mcp-evals) rather than a tool provider.

• Add explicit tool description: server.tool('add', 'Adds two numbers together and returns their sum. Use for arithmetic calculations.', {a: z.number().describe('First number'), b: z.number().describe('Second number')}, handler)
• Describe each parameter: z.number().describe('The first addend (any positive or negative number)')
• Document output schema in tool description or via response type annotations: 'Returns an object with a text field containing the numeric result as a string.'
• Add input validation and error handling: validate that a and b are finite numbers, return actionable error if not (e.g., 'Both a and b must be finite numbers; received a={a} b={b}')
• Consider renaming to 'sum_numbers' or 'calculate_sum' to match verb_noun pattern and improve clarity for LLM tool selection