MCP Client

A modular Python client for connecting to MCP servers, integrating with Anthropic Claude, and exposing a FastAPI-based API for handling queries and tool calls.

Features

• MCP Client: Connects to an MCP server (Node or Python) over stdio, negotiates available tools and manages tool calls.

• Claude AI Integration: Uses Anthropic Claude to generate natural language responses and decide when to invoke tools.

• Tool Invocation: Handles multi-turn reasoning between Claude and external tools, returning structured responses (markdown, code, chart data).

• FastAPI Server: Provides HTTP API endpoints for frontend integration.

• .env support: Loads Anthropic API keys and other environment variables from a .env file.

• CORS Support: Allows flexible frontend/backend development.

Installation

Prerequisites

• Python 3.10+

• An MCP server — e.g., mcp-node or compatible Python or Node MCP server.

• An Anthropic API Key (for Claude).

Clone the Repo

git clone https://github.com/Kiran1689/mcp-proxy-server
cd mcp-proxy-server

Install the Python Dependencies

It's recommended to use a virtual environment:

python -m venv .venv
source .venv/bin/activate  # On Windows: .venv\Scripts\activate
uv sync

Configure Environment Variables

Create a .env file in the project root:

ANTHROPIC_API_KEY=your-anthropic-api-key-here   

Usage

1. Launch your MCP Server

Follow your MCP server's instructions (e.g., NodeJS or Python). Example for Node:

cd /path/to/mcp-node
npm install
npm run start

2. Run the FastAPI Server

uvicorn client_server:app --reload

By default, this will:

• Connect to your MCP server

• Expose endpoints at http://localhost:8000

API Endpoints

• POST /query — Send a user query, receives structured response from Claude (may invoke tools).

• GET /tools — Lists available server tools.

• GET /server-name — Returns server name identifier.

3. Interactive Local Client (CLI)

You can run the interactive CLI for experimenting directly:

python client.py

Code Structure

• client.py — Implements MCPClient: connects to the MCP server, interfaces with Claude, manages conversation state, processes tool calls, and structures responses.

• client_server.py — Launches a FastAPI server, provides API endpoints, manages single MCPClient instance.

• pyproject.toml — Python packaging and dependencies.

Customizing

• You can update the system prompt for Claude in client.py to control formatting, chart standards, or code output.

• Tool schemas are detected live from your MCP server.

• Extend or replace tool invocation logic as needed.

Troubleshooting

• Check .env is present and contains your Anthropic key.

• Ensure server path/config in client.py matches your MCP server.

• View server/console logs for debugging info on tool calls and Claude's responses.

License

MIT

Contributions & issues welcome!

Feel free to submit pull requests or questions.

Built with 💙 by Kiran