mcp-builder

Use the official MCP TypeScript SDK's McpServer class and registerTool method with Zod schemas for input validation. Initialize the server with a name following the {service}-mcp-server convention, then connect via StdioServerTransport for local use or StreamableHTTPServerTransport for remote deployment.

TypeScript is recommended due to high-quality SDK support, static typing, and strong linting tools, with FastMCP available as the Python alternative. Both SDKs support stdio and streamable HTTP transports, so choose based on your existing stack and deployment environment.

Use stdio for local integrations and command-line tools running as subprocesses, and streamable HTTP for remote servers serving multiple clients. SSE is deprecated in favor of streamable HTTP, and stdio servers must log to stderr rather than stdout.

Create an XML evaluation file with 10 complex, read-only questions having single verifiable answers, then run the evaluation.py script with your transport configuration. The harness uses Claude to attempt each question and reports accuracy, tool call counts, and agent feedback on your tool design.

Tool descriptions must narrowly and unambiguously describe functionality, document parameters with types and constraints, and specify return value schemas. Include annotations like readOnlyHint and destructiveHint, use snake_case names with service prefixes like github_create_issue, and provide actionable error messages.