Code Execution MCP Server

Code Execution MCP Server

A Model Context Protocol (MCP) server that exposes Agent Zero's battle-tested code execution capabilities.

This MCP server allows any AI agent (Claude, GPT-4, etc.) to execute terminal commands and Python code on the host system using Agent Zero's proven implementation.

Features

• Execute Terminal Commands: Run shell commands with full session persistence
• Execute Python Code: Run Python code via IPython with session management
• Multiple Sessions: Maintain separate execution contexts
• Smart Output Handling: Automatic prompt detection, timeout management, and dialog detection
• Cross-Platform: Works on Linux, macOS, and Windows (experimental)

Installation

# Clone or download this package
cd code-execution-mcp

# Install dependencies
pip install -e .

# For Windows support
pip install -e ".[windows]"

Configuration

The MCP server can be configured via environment variables:

# Shell executable (default: /bin/bash on Unix, cmd.exe on Windows)
export CODE_EXEC_EXECUTABLE=/bin/bash

# Init commands (semicolon-separated, run when creating new sessions)
export CODE_EXEC_INIT_COMMANDS="source /path/to/venv/bin/activate;export PATH=\$PATH:/custom/bin"

# Timeout configuration (in seconds)
export CODE_EXEC_FIRST_OUTPUT_TIMEOUT=30      # Wait for first output
export CODE_EXEC_BETWEEN_OUTPUT_TIMEOUT=15    # Wait between output chunks
export CODE_EXEC_DIALOG_TIMEOUT=5             # Detect dialog prompts
export CODE_EXEC_MAX_EXEC_TIMEOUT=180         # Maximum execution time

MCP Client Configuration

Add to your Claude Desktop config (~/Library/Application Support/Claude/claude_desktop_config.json on macOS):

{
  "mcpServers": {
    "code-execution": {
      "command": "python",
      "args": ["/Users/lazy/Projects/A0-code-tool-MCP/code-execution-mcp/main.py"],
      "env": {
        "CODE_EXEC_EXECUTABLE": "/bin/bash",
        "CODE_EXEC_INIT_COMMANDS": "source /Users/lazy/Projects/A0-code-tool-MCP/code-execution-mcp/.venv/bin/activate"
      }
    }
  }
}

Available Tools

execute_terminal

Execute a terminal command in the specified session.

Parameters:

• command (string, required): The shell command to execute
• session (integer, optional): Session number (default: 0)

Example: ``python await execute_terminal(command="ls -la", session=0) ``

execute_python

Execute Python code via IPython in the specified session.

Parameters:

• code (string, required): The Python code to execute
• session (integer, optional): Session number (default: 0)

Example: ``python await execute_python(code="import sys; print(sys.version)", session=0) ``

get_output

Get accumulated output from a terminal session.

Parameters:

• session (integer, optional): Session number (default: 0)

Example: ``python await get_output(session=0) ``

reset_terminal

Reset a terminal session, closing and reopening it.

Parameters:

• session (integer, optional): Session number (default: 0)
• reason (string, optional): Reason for the reset

Example: ``python await reset_terminal(session=0, reason="Environment corrupted") ``

Session Management

Sessions allow maintaining separate execution contexts:

• Session 0: Default session for general commands
• Session 1+: Additional sessions for isolated environments

Each session maintains:

• Shell state (environment variables, working directory)
• Command history
• Output buffer

Virtual Environment Considerations

Important: When the MCP server is launched from a virtual environment, shell sessions may NOT automatically inherit the venv activation.

Solution: Use init commands to explicitly activate your virtual environment:

{
  "env": {
    "CODE_EXEC_INIT_COMMANDS": "source /path/to/venv/bin/activate"
  }
}

Platform Support

• Linux: Fully tested and supported
• macOS: Fully tested and supported
• Windows: Experimental support via pywinpty
• Install with: pip install -e ".[windows]"
• Use cmd.exe or powershell.exe as executable
• Some features may behave differently

Architecture

This MCP server is a minimal wrapper around Agent Zero's code execution tool:

• Preserves Agent Zero's battle-tested logic
• No rewrites or reimplementations
• Uses Agent Zero's helper modules unchanged:
• tty_session.py - TTY session management
• shell_local.py - Local shell interface
• print_style.py - Output styling and logging
• strings.py - String manipulation utilities

Security

WARNING: This MCP server allows full code execution on the host system. Security is the responsibility of the MCP client.

Only use with trusted AI agents and in controlled environments.

License

MIT License

This project wraps and reuses code from Agent Zero (Copyright (c) 2025 Agent Zero, s.r.o), which is licensed under the MIT License.

See the LICENSE file for full license text and attribution details.

Credits

Built on Agent Zero's proven code execution implementation.

This MCP server preserves and reuses Agent Zero's battle-tested code:

• Core execution logic from code_execution_tool.py
• Helper modules: tty_session.py, shell_local.py, print_style.py, strings.py
• All system message prompts

All credit for the robust code execution implementation goes to the Agent Zero team.

Uses FastMCP for MCP protocol handling.