MCP Multilang Sandbox Server

You can run a local MCP server that lets Claude execute code in isolated Docker containers across multiple languages. It runs entirely on your machine, provides fast, private, and configurable code execution, and you can customize runtimes, security, and sessions to fit your needs.

How to use

After you have the MCP server running, you connect a client (such as Claude Code) to execute code, manage persistent sessions, install language-specific packages, and perform file operations within isolated containers. Use the client to add the server, verify the connection, and then submit code requests in your preferred language. You can run short snippets, keep a persistent session for a project, and install packages that persist in that session for reuse.

How to install

Prerequisites: you need Node.js 18 or newer and Docker Desktop installed on your machine. You may also install Claude Code CLI if you want built-in MCP integration.

Step 1: Clone the project and navigate into it.

git clone https://github.com/Pit-CL/mcp-multilang-sandbox.git
cd mcp-multilang-sandbox

Step 2: Install dependencies.

npm install

Step 3: Build the server.

npm run build

Step 4: Run tests (optional) to verify MCP functionality.

npm run test:mcp

Step 5: Start the MCP server locally. Use the final start command shown here to run the server process.

node dist/mcp/server.js

Manual configuration and client setup

Configure Claude Code to connect to your local MCP server. You can either add the server from Claude’s MCP management flow or manually edit your Claude settings to point to the local server.

Example manual configuration in Claude settings (local server) shows how to launch the server process and set an environment variable for logging.

{
  "mcpServers": {
    "multilang_sandbox": {
      "command": "node",
      "args": ["/path/to/mcp-multilang-sandbox/dist/mcp/server.js"],
      "env": {
        "LOG_LEVEL": "info"
      }
    }
  }
}

Available tools

sandbox_execute

Execute code in any supported language within an isolated container, returning the output.

sandbox_session

Create, list, pause, resume, or destroy persistent execution sessions.

sandbox_install

Install packages into a session with caching to speed up repeated uses.

sandbox_file_ops

Read, write, list, or delete files within a session's filesystem.

sandbox_inspect

View system statistics such as pool status, cache usage, and active sessions.

sandbox_security

Access security audit logs and related events for the MCP server.