MCP (Multi-Capability Proxy) Server

This project implements a simple MCP server using Flask. The server can host multiple "tools," where each tool exposes functionalities by calling external REST APIs.

Project Structure

.
├── mcp_server.py       # Main Flask application, loads tools and routes requests
├── config.py           # Configuration for tools (e.g., API base URLs)
├── requirements.txt    # Python dependencies
├── tools/              # Directory for tool implementations
│   ├── __init__.py     # Makes 'tools' a Python package
│   └── example_tool.py # An example tool implementation
└── README.md           # This file

Related MCP server: MCP Server

Setup and Running

1. Clone the repository (if applicable) or ensure all files are in place.

2. Create a virtual environment (recommended):

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

3. Install dependencies:

   pip install -r requirements.txt

4. Run the server:

   python mcp_server.py

   The server will start, by default on http://127.0.0.1:5001. It will also create the tools directory and a basic example_tool.py if they don't exist upon first run (though they are included in this setup).

Using the MCP Server

The server exposes the following endpoints:

• GET /: Lists all available tools and their descriptions.

• GET /<tool_name>/<action>?param1=value1&param2=value2: Executes an action for a specific tool using GET. Parameters are passed as query strings.

• POST /<tool_name>/<action>: Executes an action for a specific tool using POST. Parameters should be sent as a JSON body.

Example: Interacting with example_tool

The example_tool interacts with https://jsonplaceholder.typicode.com.

1. List available tools:

   curl http://127.0.0.1:5001/

   This will show example_tool and its available actions.

2. Get all posts (using example_tool):

   curl http://127.0.0.1:5001/example_tool/get_posts

3. Get a specific post by ID (using example_tool):

   curl http://127.0.0.1:5001/example_tool/get_post_by_id?id=1

4. Create a new post (using example_tool):

   curl -X POST -H "Content-Type: application/json" \
        -d '{"data": {"title": "My New Post", "body": "This is the content.", "userId": 1}}' \
        http://127.0.0.1:5001/example_tool/create_post

Adding New Tools

1. Create a new Python file in the tools/ directory (e.g., my_new_tool.py).

2. Implement the execute(action, params) function:

   • This function will receive the action name (string) and params (dictionary) from the request.

   • It should contain the logic to call the external API based on the action and params.

   • It must return a JSON-serializable dictionary or list.

3. Implement the get_tool_description() function:

   • This function should return a dictionary describing the tool, including its name, a general description, and a dictionary of available actions with their descriptions and parameters. See tools/example_tool.py for a template.

4. (Optional) Add configuration for your new tool in config.py and import it into your tool file.

5. Restart the MCP server. It will automatically detect and load the new tool.

Example structure for a new tool (tools/my_new_tool.py):

import requests
# from config import MY_NEW_TOOL_CONFIG # If you have config

# MY_API_BASE_URL = MY_NEW_TOOL_CONFIG.get("BASE_URL", "default_url_if_any")

def execute(action, params=None):
    if params is None:
        params = {}

    if action == "some_action":
        # api_key = params.get("api_key")
        # some_id = params.get("id")
        # response = requests.get(f"{MY_API_BASE_URL}/endpoint/{some_id}?key={api_key}")
        # response.raise_for_status()
        # return response.json()
        return {"message": f"Action 'some_action' executed with params: {params}"}
    elif action == "another_action":
        # data_payload = params.get("data")
        # response = requests.post(f"{MY_API_BASE_URL}/other_endpoint", json=data_payload)
        # response.raise_for_status()
        # return response.json()
        return {"message": f"Action 'another_action' executed with data: {params.get('data')}"}
    else:
        return {"error": f"Action '{action}' not found in my_new_tool"}

def get_tool_description():
    return {
        "name": "My New Tool",
        "description": "This tool does new and exciting things.",
        "actions": {
            "some_action": {
                "description": "Performs some action that requires an ID.",
                "params": {"id": "string (required)", "api_key": "string (optional)"},
                "method": "GET", # Or POST, PUT, DELETE
                "path_template": "/endpoint/{id}"
            },
            "another_action": {
                "description": "Performs another action that requires a data payload.",
                "params": {"data": "object (required in body)"},
                "method": "POST",
                "path_template": "/other_endpoint"
            }
        }
    }

This provides a flexible way to extend the MCP server's capabilities.