Safe Local Python Executor MCP server

Safe Local Python Executor is an MCP server that provides a secure environment for running Python code generated by LLMs. It uses Hugging Face's LocalPythonExecutor to create a basic isolation layer, allowing you to execute Python code locally without the overhead of Docker or VMs, while still maintaining security.

Features and Security

The executor offers several security features:

• Runs Python code in a controlled environment
• Uses uv in a Python virtual environment
• Blocks file I/O operations
• Restricts imports to a safe list including collections, datetime, math, random, re, and other essential libraries

This approach balances convenience with security, providing better protection than direct eval() while being easier to set up than Docker containers or VMs.

Installation Options

Via Smithery

The simplest way to install for Claude Desktop:

npx -y @smithery/cli install @maxim-saplin/mcp_safe_local_python_executor --client claude

Manual Installation

If you prefer to install manually:

1. Install uv first:

   # On macOS
   brew install uv
   
   # For other platforms, check the official docs
   # https://docs.astral.sh/uv/getting-started/installation/
   

2. Clone the repository and run:

   git clone https://github.com/your-username/mcp_safe_local_python_executor.git
   cd mcp_safe_local_python_executor
   uv run mcp_server.py
   

Configuring Claude Desktop

1. Install Claude Desktop from claude.ai

2. Edit the configuration file:

   • macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
   • Windows: %APPDATA%\Claude\claude_desktop_config.json
   • Or via Claude Desktop → Settings → Developer → "Edit Config"

3. Add this configuration (update the path to your actual installation):

{
    "mcpServers": {
        "safe-local-python-executor": {
            "command": "uv",
            "args": [
                "--directory", 
                "/path/to/mcp_local_python_executor/",
                "run",
                "mcp_server.py"
            ]
        }
    }
}

4. Restart Claude Desktop
5. The Python executor tool will appear as a hammer icon in the message input field

Usage Examples

You can ask Claude to perform Python operations like:

• "Calculate the factorial of 5 using Python"
• "Create a list of prime numbers up to 100"
• "Solve this equation (use Python): x^2 + 5x + 6 = 0"

Claude will use the safe Python executor to run the code and return the results.

How to install this MCP server

For Claude Code

To add this MCP server to Claude Code, run this command in your terminal:

claude mcp add-json "safe-local-python-executor" '{"command":"uv","args":["--directory","/path/to/mcp_local_python_executor/","run","mcp_server.py"]}'

See the official Claude Code MCP documentation for more details.

For Cursor

There are two ways to add an MCP server to Cursor. The most common way is to add the server globally in the ~/.cursor/mcp.json file so that it is available in all of your projects.

If you only need the server in a single project, you can add it to the project instead by creating or adding it to the .cursor/mcp.json file.

Adding an MCP server to Cursor globally

To add a global MCP server go to Cursor Settings > Tools & Integrations and click "New MCP Server".

When you click that button the ~/.cursor/mcp.json file will be opened and you can add your server like this:

{
    "mcpServers": {
        "safe-local-python-executor": {
            "command": "uv",
            "args": [
                "--directory",
                "/path/to/mcp_local_python_executor/",
                "run",
                "mcp_server.py"
            ]
        }
    }
}

Adding an MCP server to a project

To add an MCP server to a project you can create a new .cursor/mcp.json file or add it to the existing one. This will look exactly the same as the global MCP server example above.

How to use the MCP server

Once the server is installed, you might need to head back to Settings > MCP and click the refresh button.

The Cursor agent will then be able to see the available tools the added MCP server has available and will call them when it needs to.

You can also explicitly ask the agent to use the tool by mentioning the tool name and describing what the function does.

For Claude Desktop

To add this MCP server to Claude Desktop:

1. Find your configuration file:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json
• Linux: ~/.config/Claude/claude_desktop_config.json

2. Add this to your configuration file:

{
    "mcpServers": {
        "safe-local-python-executor": {
            "command": "uv",
            "args": [
                "--directory",
                "/path/to/mcp_local_python_executor/",
                "run",
                "mcp_server.py"
            ]
        }
    }
}

3. Restart Claude Desktop for the changes to take effect