When to use
- You want to connect your AI to an API that doesn't have an MCP yet.
- You have a half-baked MCP and want a structured way to harden it.
- You want to learn how to write quality MCPs without reading the whole spec.
What it does
- Walks you through the design: what tools to expose, how to name them, what schemas they accept.
- Generates boilerplate code (TS, Python, etc.) following best practices from the Anthropic team.
- Suggests common test cases: empty inputs, invalid arguments, rate limits.
- Reviews authentication and security setup before declaring the MCP "ready".
How to use
- Tell your AI: "I want to build an MCP for the X API using
mcp-builder". - Answer questions about the goal of the MCP.
- Generate skeleton code; iterate the tools one at a time.
- Run the suggested test suite; fix what comes up.
Best for
Solo devs building MCPs for niche APIs. Teams wanting an internal MCP for their proprietary tools. Anyone learning to write production-grade MCPs.