Xcode MCP Broker

A small localhost broker that lets multiple MCP clients share one persistent xcrun mcpbridge connection to Xcode.

With the broker, Xcode authorization normally happens once per Xcode launch. After allowing the broker connection, agents can delegate work to subagents, custom tools, and external scripts that reuse it instead of starting another bridge and requesting access again.

OpenCode ------------\
Custom MCP clients ----> localhost broker --> mcpbridge --> Xcode
Automation scripts ---/

The broker exposes a Streamable HTTP endpoint, serializes calls to Xcode, forwards progress, cancels queued work before dispatch, caches tool discovery, and reconnects when Xcode restarts or its bridge stops responding. It binds to 127.0.0.1 by default.

Requirements

• macOS with an Xcode version that provides xcrun mcpbridge

• Node.js 20 or later for source installation and development

Related MCP server: mcp-broker

Xcode compatibility

The broker does not hardcode Xcode's tools. It reads tools/list from mcpbridge and refreshes the cache when the bridge reconnects or Xcode sends a tools/list_changed notification. New, removed, or changed tools should therefore be picked up automatically after an Xcode update without requiring a broker release. Connected MCP clients are notified when the cached tool list changes.

When Xcode is running, the broker uses the mcpbridge bundled with that application and pins the bridge to its process ID. This keeps beta or side-by-side Xcode installations aligned even when xcode-select points to another version. If no Xcode process is available, the broker waits without spawning a bridge. It monitors the pinned Xcode process and creates one replacement bridge when Xcode restarts.

This has been tested with the latest Xcode 27 beta available at the time of testing. Future Xcode versions should remain compatible as long as mcpbridge continues to implement the standard MCP lifecycle and tool APIs.

If XCODE_MCP_ALLOWED_TOOLS is set, newly added tools remain hidden until they are added to that allowlist. XCODE_MCP_BRIDGE_COMMAND can still override automatic bridge selection when needed.

Installation

macOS installer

Download the latest universal macOS installer and open it with Installer. The Developer ID signed and notarized package contains its own runtime, so Node.js is not required.

The package installs for the current user:

~/Library/Application Support/XcodeMCPBroker/xcode-mcp-broker
~/Library/LaunchAgents/com.gmicc.opencode-xcode-mcp-broker.plist

The LaunchAgent starts automatically at the next login. To start it immediately after installation:

launchctl bootout gui/$(id -u)/com.gmicc.opencode-xcode-mcp-broker 2>/dev/null || true
launchctl bootstrap gui/$(id -u) "$HOME/Library/LaunchAgents/com.gmicc.opencode-xcode-mcp-broker.plist"

Source installation

Clone the repository, install dependencies, and run the tests:

git clone https://github.com/grahammckee/XcodeMCPBroker.git
cd XcodeMCPBroker
npm install
npm test

Install the broker as a user LaunchAgent:

npm run service:install

The installer uses the current Node executable and repository path, starts the broker at login, and writes logs to ~/Library/Logs/xcode-mcp-broker.log.

Xcode does not need to be open when the service starts. The broker remains available and retries until Xcode launches. Xcode may show its normal Allow dialog when the connection is first established.

OpenCode

Point OpenCode at the broker in ~/.config/opencode/opencode.json:

{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "xcode": {
      "type": "remote",
      "url": "http://127.0.0.1:7341/mcp",
      "oauth": false,
      "enabled": true
    }
  }
}

Restart OpenCode after changing its configuration.

Verification

curl --fail http://127.0.0.1:7341/healthz
npm run broker:smoke
launchctl print gui/$(id -u)/com.gmicc.opencode-xcode-mcp-broker

The smoke command waits up to 60 seconds for initial Xcode discovery, then lists the available tools and calls the read-only XcodeListWindows tool.

To run the broker in the foreground instead:

npm run broker:start

To remove the LaunchAgent:

npm run service:uninstall

To remove a package installation while retaining its logs:

"$HOME/Library/Application Support/XcodeMCPBroker/xcode-mcp-broker" uninstall

Configuration

These variables are read directly when running in the foreground. To persist an override in the LaunchAgent, provide it while installing:

XCODE_MCP_ALLOWED_TOOLS="XcodeListWindows,BuildProject" npm run service:install

The broker does not provide authentication. Keep it bound to the loopback interface unless you add an appropriate access-control layer.

Contributing

Issues and pull requests are welcome. Read CONTRIBUTING.md for development, testing, and release-label requirements. Participation is governed by the Code of Conduct.

Do not open public issues for suspected vulnerabilities. Follow the private reporting process in SECURITY.md.

Repository layout

License

Licensed under the MIT License.