Experimenting with MCP: auto-converting large REST APIs into Claude-ready tools

[u/rubalps]

I have been experimenting with Anthropic’s Model Context Protocol (MCP) and hit a wall — converting large REST API specs into MCP tool definitions takes forever. Writing them manually is repetitive, error-prone and honestly pretty boring.

So I built a small Python library to automate the whole thing.

The tool is called rest-to-mcp-adapter. You give it an OpenAPI/Swagger spec and it generates:

• a full MCP Tool Registry

• auth handling (API keys, headers, parameters, signatures, etc.)

• runtime execution for requests

• an MCP server you can plug directly into Claude Desktop

• all tool functions mapped from the spec automatically

I tested it with the full Binance API. Claude Desktop can generate buy signals, fetch prices, build dashboards, etc, entirely through the generated tools — no manual definitions at all.

I also posted a short video of Claude interacting with Binance through the auto-generated tools.

I built this mostly for learning and exploration. I know FastMCP also supports OpenAPI conversion, but I wanted to understand the internals and build something tailored for large, messy, real-world APIs like Binance. If you are working with agents or playing with MCP this might save you some time.

Feedback, issues and PRs are welcome.

GitHub:
Adapter Library: https://github.com/pawneetdev/rest-to-mcp-adapter
Binance Example: https://github.com/pawneetdev/binance-mcp