mcp-rag

Connecting a RAG application to open-webui by means of MCP

1. Bare bones MCP PoC / Hello World

pip install mcp[cli]

• look up documentation on sse snippets

• run server using uvicorn

• doesnt work -> look up documentation in SseServerTranpsort class which differs from MCP website

• change Route -> Mount for starlette_app, then it works

• starlette gives 307 temporary redirect, testing it with curl shows that it is due to a missing trailing slash

• looked up on github repo, there the routes end with trailing slash for server code, especially the sse = SseServerTransport("/messages/") part which I guess tells the client what to call

• add some prompts and check on client side

Writeup

• I want to try out the model context protocol because I have been experimenting with RAG prototypes for use with open-webui. MCP looks similar to LSP. Since server and client won't be on the same machine, we have to use the SSE transport.

• MCP comes with some snippets on the official documentation, I had to adapt them a bit following the docstrings provided by the mcp python library. Took me a while to get things working, initially dealt with 307 Temporary Redirect errors since the server was sending the wrong endpoint.

• Test it! Build a small REPL that can interact with the server

Goal

1. understand what MCP is

2. implement a simple server and client

3. try out function calling / tool usage

Related MCP server: OpenAI MCP Server

2. Implement a basic KnowlegdeBase

• I want to build a simple KnowledgeBase that we can stick into the MCP server and call through the client to retrieve some context.

3. MCP Client + Open-WebUI