MCP Async Tool Proxy Server

A Model Context Protocol server that acts as an asynchronous proxy for other MCP servers.

This server provides the same tools as a target MCP server, but instead of returning results immediately, it creates resources that are updated with the results when tool calls complete asynchronously.

This allows an agent to fire off a long-running task and periodically check the results while continuing other elements of its task without having its progress blocked while the task is running.

Features

Tools

• Proxy all tools from target server - Any tool available on the target MCP server
  • Tool calls are executed asynchronously
  • Returns operation ID and resource URI for tracking progress
  • Results are stored in resources when complete

Resources

• List and access async operation status via async://operation/ URIs
• Each operation tracks the status, arguments, and results of async tool calls
• JSON format for structured data access

Configuration

The server requires environment variables to configure the target MCP server:

• targetUrl - like http://localhost:3001
• mcpPort - defaults to 3000

Running

node src/index.ts --mcpPort 3000 --targetUrl http://localhost:3001

or npx .