mcp-rag-server - RAG MCP Server

mcp-rag-server is a Model Context Protocol (MCP) server that enables Retrieval Augmented Generation (RAG) capabilities. It empowers Large Language Models (LLMs) to answer questions based on your document content by indexing and retrieving relevant information efficiently.

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Table of Contents

• Overview
• MCP Server Usage
  • Basic Configuration
  • Advanced Configuration
• Installation
  • From Source
• Available RAG Tools
• How RAG Works
• Environment Variables
  • Default Environment Settings
  • Configuration Examples for Embedding Providers
• Integrating with Your Client and AI Agent
  • Example Chat Conversation
• Development
• Contributing
• License

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Overview

mcp-rag-server allows you to seamlessly integrate RAG functionalities into your applications. It works by:

• Indexing: Parsing documents and splitting them into manageable chunks.
• Embedding: Generating vector embeddings for each text chunk.
• Querying: Matching query embeddings with stored document chunks to retrieve context.

This enables downstream LLMs (via MCP clients like Claude Desktop) to generate contextually relevant responses.

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MCP Server Usage

Basic Configuration

Integrate the server with your MCP client by adding the following to your configuration:

{
  "mcpServers": {
    "rag": {
      "command": "npx",
      "args": ["-y", "mcp-rag-server"]
    }
  }
}

Note: Ensure that the required environment variables are set in the environment where your MCP client runs the command.

Advanced Configuration

For custom settings, including environment variables:

{
  "mcpServers": {
    "rag": {
      "command": "npx",
      "args": ["-y", "mcp-rag-server"],
      "env": {
        "BASE_LLM_API": "http://localhost:11434/v1",
        "LLM_API_KEY": "",
        "EMBEDDING_MODEL": "granite-embedding-278m-multilingual-Q6_K-1743674737397:latest",
        "VECTOR_STORE_PATH": "/user-dir/vector_store_locate/",
        "CHUNK_SIZE": "500"
      }
    }
  }
}

Note: Environment variable configuration via the client depends on its capabilities. System-level environment variables are generally recommended.

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Installation

From Source

1. Clone the Repository:

   git clone https://github.com/yourusername/mcp-rag-server.git
   cd mcp-rag-server
   

2. Install Dependencies:

   npm install
   

3. Build the Project:

   npm run build
   

4. Run the Server:

   Ensure your environment variables are set, then start the server:

   npm start
   

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Available RAG Tools

The server provides the following operations accessible via MCP:

• index_documents:
  Index documents from a directory or a single file.
  Supported file types: .txt, .md, .json, .jsonl, .csv

• query_documents:
  Retrieve context by querying the indexed documents using RAG.

• remove_document:
  Delete a specific document from the index by its path.

• remove_all_documents:
  Clear the entire document index (confirmation required).

• list_documents:
  Display all indexed document paths.

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How RAG Works

The RAG process in the server consists of the following steps:

1. Indexing:
   The index_documents tool accepts a file or directory path to begin processing.

2. Chunking & Embedding:
   The server splits documents into chunks (configurable via CHUNK_SIZE) and generates vector embeddings using the specified EMBEDDING_MODEL via the BASE_LLM_API.

3. Storing:
   The embeddings and chunks are stored in a local vector database at the path specified by VECTOR_STORE_PATH.

4. Querying:
   When query_documents is called, the server generates an embedding for your query.

5. Searching:
   It retrieves the top k document chunks that match the query.

6. Contextualization:
   The retrieved chunks are returned as context to your LLM, which then generates a final answer.

flowchart LR
    A[User provides document path via index_documents] --> B(RAG Server Reads & Chunks Docs)
    B --> C{Generate Embeddings via LLM API}
    C --> D[Store Embeddings & Chunks in Vector DB]
    E[User asks question via query_documents] --> F{Generate Query Embedding}
    F --> G{Search Vector DB}
    G -- Top k Chunks --> H[Return Context to User/Client]
    H --> I(Client/LLM Generates Final Answer)

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Environment Variables

The server relies on several environment variables. These can be set at the system level or passed via your MCP client configuration.

Default Environment Settings

If not explicitly set, the following defaults from the code will be used:

• BASE_LLM_API (Required)
  The base URL for the embedding API endpoint.
  Default: http://localhost:11434/v1

• LLM_API_KEY (Optional)
  API key for the embedding service (if required).
  Default: "" (empty string)

• EMBEDDING_MODEL (Required)
  The embedding model to use with the API.
  Default: granite-embedding-278m-multilingual-Q6_K-1743674737397:latest

• VECTOR_STORE_PATH (Optional)
  The directory path for storing the vector database.
  Default: ./vector_store

• CHUNK_SIZE (Optional)
  The target size (in characters) for splitting documents into chunks.
  Default: 500

Configuration Examples for Embedding Providers

1. Ollama (Local)

• Setup:
  • Ensure Ollama is running and the desired model is pulled (e.g., ollama pull nomic-embed-text).
• Variables:

  BASE_LLM_API=http://localhost:11434/v1
  LLM_API_KEY=
  EMBEDDING_MODEL=nomic-embed-text
  

2. LM Studio (Local)

• Setup:
  • Start the LM Studio server and load an embedding model.
• Variables:

  BASE_LLM_API=http://localhost:1234/v1
  LLM_API_KEY=
  EMBEDDING_MODEL=lm-studio-model
  

3. OpenAI API

• Setup:
  • Use your OpenAI credentials.
• Variables:

  BASE_LLM_API=https://api.openai.com/v1
  LLM_API_KEY=YOUR_OPENAI_API_KEY
  EMBEDDING_MODEL=text-embedding-ada-002
  

4. OpenRouter

• Setup:
  • Use your OpenRouter API key.
• Variables:

  BASE_LLM_API=https://openrouter.ai/api/v1
  LLM_API_KEY=YOUR_OPENROUTER_API_KEY
  EMBEDDING_MODEL=openai/text-embedding-ada-002
  

5. Google Gemini (via OpenAI Compatibility Endpoint)

• Setup:
  • Follow Google’s instructions to enable the compatibility endpoint.
• Variables:

  BASE_LLM_API=https://generativelanguage.googleapis.com/v1beta
  LLM_API_KEY=YOUR_GEMINI_API_KEY
  EMBEDDING_MODEL=embedding-001
  

Important: Always refer to your provider’s documentation for precise API endpoints, model names, and authentication requirements.

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Integrating with Your Client and AI Agent

After setting up the MCP server, integrate it with your client (or AI agent) so that it can leverage RAG operations seamlessly.

Configuring Your MCP Client

Ensure your client configuration includes the RAG server as shown below:

{
  "mcpServers": {
    "rag": {
      "command": "npx",
      "args": ["-y", "mcp-rag-server"],
      "env": {
        "BASE_LLM_API": "http://localhost:11434/v1",
        "LLM_API_KEY": "",
        "EMBEDDING_MODEL": "granite-embedding-278m-multilingual-Q6_K-1743674737397:latest",
        "VECTOR_STORE_PATH": "./vector_store",
        "CHUNK_SIZE": "500"
      }
    }
  }
}

Example Chat Conversation

Below is an example conversation that demonstrates how an AI agent might instruct the MCP server to index documents and query the indexed documents:

User:
Hey, can you add my documents for indexing? I have them stored in /data/docs.

AI Agent:
Sure, let me index the documents from /data/docs now.

([Tool Call]: The agent issues an "index_documents" command with the path /data/docs.)

AI Agent (after processing):
The documents have been successfully indexed.

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User:
Great! Now, could you help me find out what the main topics are in our latest report?

AI Agent:
Okay, I'll query the indexed documents to retrieve context related to your report.

([Tool Call]: The agent issues a "query_documents" command with the query "What are the main topics in our latest report?")

AI Agent (after processing):
I found some relevant context from your documents. Based on the retrieved information, the main topics include market trends, customer feedback, and upcoming product features.

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Development

Prerequisites

• Node.js (see package.json for version requirements)
• npm

Building

npm run build

Testing

To be implemented:

# npm test

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Contributing

Contributions are welcome! If you wish to propose changes or add features, please:

• Open an issue for discussion before submitting a pull request.
• Follow the code style and commit guidelines provided in the repository.

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License

This project is licensed under the MIT License.