MCP Backend Pattern

For services that expose an MCP (Model Context Protocol) server instead of a traditional CLI.

When to Use

The software has an official or community MCP server
No native CLI exists, or MCP provides better functionality
You want to integrate AI/agent tools that speak MCP protocol

Use case: When the software provides an MCP server instead of a traditional CLI. Example: DOMShell provides browser automation via MCP tools.

Backend Wrapper (`utils/<service>_backend.py`)

import asyncio
from typing import Any
from mcp import ClientSession, StdioServerParameters
from mcp.client.stdio import stdio_client

async def _call_tool(tool_name: str, arguments: dict) -> Any:
    """Call an MCP tool."""
    server_params = StdioServerParameters(
        command="npx",
        args=["@apireno/domshell"]
    )
    async with stdio_client(server_params) as (read, write):
        async with ClientSession(read, write) as session:
            await session.initialize()
            result = await session.call_tool(tool_name, arguments)
            return result

def is_available() -> bool:
    """Check if MCP server is available."""
    # Try to spawn and verify
    ...

# Sync wrappers for each tool
def ls(path: str = "/") -> dict:
    """List directory contents."""
    return asyncio.run(_call_tool("domshell_ls", {"path": path}))

Session Management

MCP server spawns per command (stateless from server perspective)
CLI maintains state (URL, working directory, navigation history)
Each command re-spawns the MCP server process

Daemon Mode (Optional)

Spawn MCP server once, reuse connection for multiple commands
Reduces latency for interactive use
Requires explicit start/stop or --daemon flag

Dependencies

Add mcp>=0.1.0 to install_requires.

Example Implementations

browser/agent-harness — DOMShell MCP server for browser automation
See: https://github.com/HKUDS/CLI-Anything/tree/main/browser/agent-harness

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