MCP Baepsae

🚀 mcp-baepsae

A local MCP server for iOS Simulator and macOS app automation with a TypeScript MCP layer and a Swift native bridge.

Baepsae (Vinous-throated Parrotbill) — A tiny Korean bird. Round, chubby, and constantly hopping around chirping. Known for its grit — even when a little bird tries to keep up with a stork, it never gives up. This project is small too, but it pecks away at your simulators tirelessly.

Korean documentation can be found in README-KR.md.

🚀 Quick Start

mcp-baepsae is a local MCP server for iOS Simulator and macOS app automation. It combines a TypeScript MCP layer and a Swift native bridge to provide seamless interaction with simulators and applications.

✨ Features

• Local MCP server for iOS Simulator and macOS app automation.
• TypeScript MCP layer for easy integration.
• Swift native bridge for better performance.
• Support for multiple clients and LLMs.

📦 Installation

Prerequisites

• macOS 14+
• Xcode + iOS Simulator
• Node.js 18+
• Swift 6+

Installation Options

Option A) npm (easiest)

# Run directly without installing
npx mcp-baepsae@latest

# Or install globally
npm install -g mcp-baepsae

On macOS, the Swift native binary is built automatically during install. If Swift is not available, the server still works with simctl-based features.

Option B) From source

git clone https://github.com/oozoofrog/mcp-baepsae.git
cd mcp-baepsae
npm install
npm run build

💻 Usage Examples

Simulator app accessibility quickstart (inside app UI):

// 1) Launch your app in the target simulator
launch_app({ udid: "...", bundleId: "com.example.app" })

// 2) Inspect or search accessibility tree (in-app content scope by default)
sim_describe_ui({ udid: "..." })
sim_search_ui({ udid: "...", query: "Login" })

// 3) Interact by accessibility identifier/label
sim_tap({ udid: "...", id: "login-button" })

// Optional: include Simulator chrome/system UI in selector lookup
sim_tap({ udid: "...", label: "Home", all: true })

Open a URL (iOS Simulator):

// Open Naver Mobile
open_url({ udid: "...", url: "https://m.naver.com" })

Manage Apps (iOS Simulator):

// Install an app
install_app({ udid: "...", path: "/path/to/App.app" })

// Launch Safari
launch_app({ udid: "...", bundleId: "com.apple.mobilesafari" })

// Terminate Safari
terminate_app({ udid: "...", bundleId: "com.apple.mobilesafari" })

macOS App Automation:

// List running macOS apps
list_apps({})

// Take screenshot of a macOS app
mac_screenshot_app({ bundleId: "com.apple.Safari" })

📚 Documentation

Platform Support

Why macOS only?

The Swift native bridge (baepsae-native) uses macOS-specific frameworks (AppKit, CoreGraphics, Accessibility) to interact with iOS Simulator and macOS applications. These frameworks are not available on Linux or Windows. The TypeScript MCP layer also relies on xcrun simctl, which is part of Xcode Command Line Tools and only available on macOS.

Requirements summary:

• macOS 14 or later -- required for iOS Simulator automation and Accessibility API access.
• Xcode or Xcode Command Line Tools -- required for Swift 6+ compilation of the native binary and xcrun simctl commands.
• Node.js >= 18.0.0 -- required to run the TypeScript MCP server.

Permissions

Accessibility permission is required for UI inspection and input automation features (use sim_* / mac_* scoped tools such as sim_describe_ui, mac_tap, sim_right_click).

1. Open System Settings > Privacy & Security > Accessibility.
2. Enable the MCP client app and terminal you actually use, and also the runtime process (node) if listed.
3. If the app is missing, click + and add it manually.

For simulator targets, selector-based actions (sim_tap / sim_right_click with id or label) search in-app content by default. Set all: true to include Simulator chrome UI.

MCP Setup (Recommended)

Use the installer script that calls each client's MCP install flow directly.

bash scripts/install.sh --tool all

Client Matrix

For LLM

If you are an LLM agent setting up this MCP server, here is everything you need:

Quick start (one command)

# Register baepsae as an MCP server for all supported clients
bash scripts/install.sh --tool all

If you installed via npm instead of cloning the repo, use npx:

# Claude Code
claude mcp add baepsae -- npx -y mcp-baepsae@latest

# Codex CLI
codex mcp add baepsae -- npx -y mcp-baepsae@latest

Automation flags

# Preview commands without executing
bash scripts/install.sh --tool all --dry-run

# Verify environment and dependencies
bash scripts/install.sh --tool all --doctor

# Unregister from all clients
bash scripts/install.sh --tool all --uninstall

Runtime options

The installer supports multiple runtimes via --runtime:

Manual Setup (Fallback)

Use this when you do not want to run scripts/install.sh.

Using npx (recommended for npm users)

# Claude Code
claude mcp add baepsae -- npx -y mcp-baepsae@latest

# Codex CLI
codex mcp add baepsae -- npx -y mcp-baepsae@latest

# Gemini CLI
gemini mcp add --scope user --transport stdio baepsae npx -y mcp-baepsae@latest

Using local build

# Claude Code (project)
claude mcp add --scope project --env="BAEPSAE_NATIVE_PATH=/ABS/PATH/native/.build/release/baepsae-native" baepsae -- node /ABS/PATH/dist/index.js

# Codex CLI
codex mcp add baepsae --env BAEPSAE_NATIVE_PATH=/ABS/PATH/native/.build/release/baepsae-native -- node /ABS/PATH/dist/index.js

# Gemini CLI
gemini mcp add --scope user --transport stdio -e BAEPSAE_NATIVE_PATH=/ABS/PATH/native/.build/release/baepsae-native baepsae node /ABS/PATH/dist/index.js

Project Structure

• MCP server entry point: src/index.ts
• Tool modules: src/tools/ (info, simulator, ui, input, media, system)
• Shared utilities: src/utils.ts, src/types.ts
• Native binary entry point: native/Sources/main.swift
• Native command handlers: native/Sources/Commands/
• Native binary output: native/.build/release/baepsae-native
• TS tests: tests/mcp.contract.test.mjs, tests/unit.test.mjs, tests/mcp.real.test.mjs
• Swift tests: native/Tests/BaepsaeNativeTests/

Commands

npm run build       # Build TypeScript + native Swift binary
npm test            # Contract/integration tests
npm run test:real   # Real simulator smoke test (requires booted simulator)
npm run verify      # test + test:real
npm run setup:mcp   # Alias for scripts/install.sh

MCP Tool Status

47 tools implemented end-to-end.

Explicit target-scoped tools (30, recommended)

Use these first to avoid simulator/macOS target ambiguity.

iOS Simulator Only (11)

list_simulators, screenshot, record_video, stream_video, open_url, install_app, launch_app, terminate_app, uninstall_app, button, gesture

macOS / System Only (4)

list_apps, menu_action, get_focused_app, clipboard

Utility (2)

baepsae_help, baepsae_version

🔧 Technical Details

The Swift native bridge (baepsae-native) uses macOS-specific frameworks (AppKit, CoreGraphics, Accessibility) to interact with iOS Simulator and macOS applications. These frameworks are not available on Linux or Windows. The TypeScript MCP layer also relies on xcrun simctl, which is part of Xcode Command Line Tools and only available on macOS.

📄 License

No license information provided in the original document.

Troubleshooting

• Invalid environment variable format on Claude setup:
  • Use current script (scripts/install.sh) or claude mcp add --env="KEY=value" ... format.
• Missing native binary error:
  • Run npm run build and confirm native/.build/release/baepsae-native exists.
• OpenCode does not show baepsae:
  • Re-run bash scripts/install.sh --tool opencode --skip-install --skip-build and check ~/.config/opencode/opencode.json.
• Copilot not auto-registered:
  • Copilot MCP flow is interactive/session-based. Re-run installer with --interactive.
• Real smoke test skipped:
  • Boot an iOS simulator first, then run npm run test:real.