MCP Builder

What it does

MCP Builder is a guide in skill form. It walks Claude through building an MCP server that wraps an external API: planning the tools, writing them in Python (FastMCP) or TypeScript, and testing them.

Why it is useful

• Good tool design (clear names, focused inputs, useful errors) is the hard part of MCP. This skill builds it in.
• It ends with testing in the MCP Inspector, so you ship a server that works.

How to use it

/plugin marketplace add anthropics/skills

Then ask Claude to build an MCP server for the API you want to connect.

Watch out for

• You still own the API keys and the security of what the server can do.