async-bash-mcp 0.1.4

A robust subprocess execution MCP

async-bash-mcp

An MCP server for spawning and managing bash commands asynchronously. Run multiple shell commands in parallel and check their progress independently.

Usage with opencode

Add to your opencode.json config to replace the bash tool with async-bash-mcp:

{
  "$schema": "https://opencode.ai/config.json",
  "tools": {
    "bash": false
  },
  "mcp": {
    "async-bash": {
      "type": "local",
      "command": ["uvx", "async-bash-mcp"],
      "enabled": true
    }
  }
}

Then use commands like:

• "Spawn a long-running build in the background"
• "Run tests in parallel and show me the results"
• "Start a server and tell me when it's ready"

Why async bash?

When working with long-running commands like builds, tests, or servers, the agent needs to:

• Monitor progress incrementally without committing to a fixed timeout
• Run multiple commands in parallel and check each independently
• Make decisions about continuing or terminating based on partial output
• Process real-time feedback as commands generate output

This tool provides the agent with better information for decision-making, leading to faster task completion and fewer confused responses.

Key advantages over the built-in bash tool:

• Better decision making: Agents can see partial output and make informed choices about continuing or terminating
• Parallel execution: Run multiple commands simultaneously
• No timeout guessing: Check progress incrementally instead of setting timeouts upfront
• Faster iterations: No waiting for arbitrary timeouts when errors are already visible

This tool is designed to replace opencode's bash tool for any scenario involving potentially long-running commands, giving agents the information they need to make better decisions and save you time.

Tools

spawn - Launch a bash command asynchronously

• command (str): The bash command to run
• cwd (str, optional): Working directory path
• Returns a process ID for tracking

list_processes - Show all running/recent processes

• No parameters
• Returns array of {"ID": int, "command": str, "done": bool}

poll - Check progress of a spawned process

• process_id (int): ID from spawn command
• wait (int): Wait time in milliseconds
• terminate (bool, optional): Kill process before returning results
• Returns {"stdout": str, "stderr": str, "elapsedTime": float, "finished": bool, "exitCode": int}

Installation

uvx async-bash-mcp