Pexpect MCP

🚀 pexpect-mcp

An MCP (Model Context Protocol) server that provides remote pexpect session control for debugging and process interaction.

🚀 Quick Start

This MCP server enables AI assistants to execute Python code with pexpect functionality, allowing for interactive debugging sessions with tools like LLDB, GDB, and other command - line utilities that require programmatic interaction. In some sense, this is less of a pexpect MCP as one that is just maintaining a stateful Python session.

📦 Installation

uv tool install git+https://github.com/mitsuhiko/pexpect-mcp

💻 Usage Examples

Basic Usage

As an MCP Server

Add to your Claude Code configuration:

{
  "mcpServers": {
    "pexpect": {
      "command": "pexpect-mcp"
    }
  }
}

Tool Usage

The server provides a single tool: pexpect_tool

Parameters:

• code (string): Python code to execute with pexpect support
• timeout (optional int): Timeout in seconds (default: 30)

Advanced Usage

# Start a debugging session
child = pexpect.spawn('lldb ./my-program')
child.expect('(lldb)')

# Run the program
child.sendline('run')
child.expect('(lldb)')
print(child.before.decode())

# Get backtrace
child.sendline('bt')
child.expect('(lldb)')
print(child.before.decode())

🔧 Technical Details

The repository includes a demo with a buggy C program (demo-buggy.c) that can be debugged using LLDB through the pexpect interface. This demonstrates the server's capability for interactive debugging sessions.

The program `./demo-buggy` crashes when executed. Use LLDB to:

- Start the program under the debugger
- Identify where and why it crashes
- Examine variables, memory, and call stack
- Report the root cause of the crash

Requirements

📄 License

See LICENSE file for details.