Safe Local Python Executor/Interpreter

# Safe Local Python Executor An MCP server (stdio transport) that wraps Hugging Face's [`LocalPythonExecutor`](https://github.com/huggingface/smolagents/blob/main/src/smolagents/local_python_executor.py) (from the [`smolagents`](https://huggingface.co/docs/smolagents/en/index) framework). It is a custom Python runtime that provides basic isolation/security when running Python code generated by LLMs locally. It does not require Docker or VM. This package allows to expose the Python executor via MCP (Model Context Protocol) as a tool for LLM apps like Claude Desktop, Cursor or any other MCP compatible client. In case of Claude Desktop this tool is an easy way to add a missing Code Interpreter (available as a plugin in ChatGPT for quite a while already). <img width="1032" alt="image" src="https://github.com/user-attachments/assets/3b820bfc-970a-4315-8f2d-970591c6fdae" /> ## Features - Exposes `run_python` tool - Safer execution of Python code compared to direct use of Python `eva()l` - Ran via uv in Python venv - No file I/O ops are allowed - Restricted list of imports - collections - datetime - itertools - math - queue - random - re - stat - statistics - time - unicodedata ## Security Be careful with execution of code produced by LLM on your machine, stay away from MCP servers that run Python via command line or using `eval()`. The safest option is using a VM or a docker container, though it requires some effort to set-up, consumes resources/slower. There're 3rd party servcices providing Python runtime, though they require registration, API keys etc. `LocalPythonExecutor` provides a good balance between direct use of local Python environment (which is easier to set-up) AND remote execution in Dokcer container or a VM/3rd party service (which is safe). Hugginng Face team has invested time into creating a quick and safe option to run LLM generated code used by their code agents. This MCP server builds upon it: >To add a first layer of security, code execution in smolagents is not performed by the vanilla Python interpreter. We have re-built a more secure LocalPythonExecutor from the ground up. Read more [here](https://huggingface.co/docs/smolagents/en/tutorials/secure_code_execution#local-code-execution). ## Installation and Execution 1. Install `uv` (e.h. `brew install uv` on macOS or use [official docs](https://docs.astral.sh/uv/getting-started/installation/#__tabbed_1_2)) 2. Clone the repo, change the directory `cd mcp_safe_local_python_executor` 3. The server can be started via command line `uv run mcp_server.py`, venv will be created automatically, depedencies (smollagents, mcp) will be installed ## Configuring Claude Desktop 1. Make sure you have Claude for Desktop installed (download from [claude.ai](https://claude.ai/desktop)) 2. Edit your Claude for Desktop configuration file: - macOS: `~/Library/Application Support/Claude/claude_desktop_config.json` - Windows: `%APPDATA%\Claude\claude_desktop_config.json` - Or open Claude Desktop -> Settings -> Developer -> click "Edit Config" button 3. Add the following configuration: ```json { "mcpServers": { "safe-local-python-executor": { "command": "uv", "args": [ "--directory", "/path/to/mcp_local_python_executor/", "run", "mcp_server.py" ] } } } ``` 4. Restart Claude for Desktop 5. The Python executor tool will now be available in Claude (you'll see hammer icon in the message input field) ## Example Prompts Once configured, you can use prompts 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" ## Development Clone the repo. Use `uv` to create venv, install dev dependencies, run tests: ``` uv venv .venv uv sync --group dev python -m pytest tests/ ``` ----------------------- <a href="https://glama.ai/mcp/servers/@maxim-saplin/mcp_safe_local_python_executor"> <img width="380" height="200" src="https://glama.ai/mcp/servers/@maxim-saplin/mcp_safe_local_python_executor/badge" /> </a>