MCP Utils

A Python package with utilities and helpers for building MCP-compliant servers, often using Flask and Redis.

GitHub

mcp-utils

A Python utility package for building Model Context Protocol (MCP) servers.

Tests PyPI - Version

Table of Contents

Overview

mcp-utils provides utilities and helpers for building MCP-compliant servers in Python, with a focus on synchronous implementations using Flask. This package is designed for developers who want to implement MCP servers in their existing Python applications without the complexity of asynchronous code.

Key Features

  • Basic utilities for MCP server implementation
  • Server-Sent Events (SSE) support
  • Simple decorators for MCP endpoints
  • Synchronous implementation
  • HTTP protocol support
  • Redis response queue
  • Comprehensive Pydantic models for MCP schema
  • Built-in validation and documentation

Installation

pip install mcp-utils

Requirements

  • Python 3.10+
  • Pydantic 2

Optional Dependencies

  • Flask (for web server)
  • Gunicorn (for production deployment)
  • Redis (for response queue)

Usage

Basic MCP Server

Here's a simple example of creating an MCP server:

from mcp_utils.core import MCPServer
from mcp_utils.schema import GetPromptResult, Message, TextContent, CallToolResult

# Create a basic MCP server
mcp = MCPServer("example", "1.0")

@mcp.prompt()
def get_weather_prompt(city: str) -> GetPromptResult:
    return GetPromptResult(
        description="Weather prompt",
        messages=[
            Message(
                role="user",
                content=TextContent(
                    text=f"What is the weather like in {city}?",
                ),
            )
        ],
    )

@mcp.tool()
def get_weather(city: str) -> str:
    return "sunny"

Flask Example

For production use, you can use a simple Flask app with the mcp server and support Streamable HTTP from version 2025-06-18.

from flask import Flask, Response, url_for, request

# Create Flask app and MCP server with Redis queue
app = Flask(__name__)
mcp = MCPServer(
    "example",
    "1.0",
)

@app.route("/mcp", methods=["POST"])
def mcp_route():
    response = mcp.handle_message(request.get_json())
    return jsonify(response.model_dump(exclude_none=True))


if __name__ == "__main__":
    app.run(debug=True)

SQLAlchemy Transaction Handling Example

For production use, you can integrate the MCP server with Flask, Redis, and SQLAlchemy for better message handling and database transaction management:

from flask import Flask, request
from sqlalchemy.orm import Session
from sqlalchemy import create_engine

# Create engine for PostgreSQL database
engine = create_engine("postgresql://user:pass@localhost/dbname")

# Create Flask app and MCP server with Redis queue
app = Flask(__name__)
mcp = MCPServer(
    "example",
    "1.0",
)

@app.route("/mcp", methods=["POST"])
def mcp_route():
    with Session(engine) as session:
        try:
            response = mcp.handle_message(request.get_json())
            session.commit()
        except:
            session.rollback()
            raise
        else:
            return jsonify(response.model_dump(exclude_none=True))


if __name__ == "__main__":
    app.run(debug=True)

For a more comprehensive example including logging setup and session management, check out the example Flask application in the repository.

Running with Gunicorn

Gunicorn is a better approach to running even locally. To run the app with gunicorn

from gunicorn.app.base import BaseApplication

class FlaskApplication(BaseApplication):
    def __init__(self, app, options=None):
        self.options = options or {}
        self.application = app
        super().__init__()

    def load_config(self):
        config = {
            key: value
            for key, value in self.options.items()
            if key in self.cfg.settings
        }
        for key, value in config.items():
            self.cfg.set(key.lower(), value)

    def load(self):
        return self.application


if __name__ == "__main__":
    handler = logging.StreamHandler(sys.stdout)
    formatter = logging.Formatter("[%(asctime)s] [%(levelname)s] %(name)s: %(message)s")
    handler.setFormatter(formatter)
    logger.addHandler(handler)
    options = {
        "bind": "0.0.0.0:9000",
        "workers": 1,
        "worker_class": "gevent",
        "loglevel": "debug",
    }
    FlaskApplication(app, options).run()

Connecting with MCP Clients

Cursor

  • Edit MCP settings and add to configuration
{
  "mcpServers": {
    "server-name": {
      "url": "http://localhost:9000/mcp"
    }
  }
}

Claude Desktop

As of this writing, Claude Desktop does not support MCP through SSE and only supports stdio. To connect Claude Desktop with an MCP server, you'll need to use mcp-proxy.

Configuration example for Claude Desktop:

{
  "mcpServers": {
    "weather": {
      "command": "/Users/yourname/.local/bin/mcp-proxy",
      "args": ["http://127.0.0.1:9000/sse"]
    }
  }
}

Installing via Smithery

To install MCP Proxy for Claude Desktop automatically via Smithery:

npx -y @smithery/cli install mcp-proxy --client claude

Installing via PyPI

The stable version of the package is available on the PyPI repository. You can install it using the following command:

# Option 1: With uv (recommended)
uv tool install mcp-proxy

# Option 2: With pipx (alternative)
pipx install mcp-proxy

Once installed, you can run the server using the mcp-proxy command.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

Related Projects

  • MCP Python SDK - The official async Python SDK for MCP
  • mcp-proxy - A proxy tool to connect Claude Desktop with MCP servers

License

MIT License

Testing with MCP Inspector

The MCP Inspector is a useful tool for testing and debugging MCP servers. It provides a web interface to inspect and test MCP server endpoints.

Installation

Install MCP Inspector using npm:

npm install -g @modelcontextprotocol/inspector

Usage

  1. Start your MCP server (e.g., the Flask example above)
  2. Run MCP Inspector:
git clone [email protected]:modelcontextprotocol/inspector.git
cd inspector
npm run build
npm start
  1. Open your browser and navigate to http://127.0.0.1:6274/
  2. Enter your MCP server URL (e.g., http://localhost:9000/sse)
  3. Use the inspector to:
    • Change transport type to SSE
    • Test server connections
    • Monitor SSE events
    • Send test messages
    • Debug responses

This tool is particularly useful during development to ensure your MCP server implementation is working correctly and complies with the protocol specification.

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