mcp-baepsae

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.

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

한국어 문서는 README-KR.md를 참고하세요.

Table of Contents

• Prerequisites
• Platform Support
• Install
• Permissions
• MCP Setup (Recommended)
• Client Matrix
• For LLM
• Manual Setup (Fallback)
• Project Structure
• Commands
• MCP Tool Status
• Usage Examples
• Troubleshooting

Prerequisites

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

Platform Support

Platform	Supported	Notes
macOS	Yes	Primary platform. Required for iOS Simulator and Accessibility APIs.
Linux	No	Native binary depends on AppKit, CoreGraphics, and Accessibility frameworks.
Windows	No	Native binary depends on AppKit, CoreGraphics, and Accessibility frameworks.

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.

Install

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

MCP Setup (Recommended)

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

bash scripts/install.sh --tool all

Client Matrix

Client	Install Path	Script Target	Notes
Claude Code	claude mcp add	--tool claude-code	Supports multi-scope via --claude-scope
Claude Desktop	claude mcp add --scope user	--tool claude-desktop	User-level registration
Codex CLI	codex mcp add	--tool codex-cli	Also works for Codex Desktop settings
Codex Desktop	Codex CLI MCP config	--tool codex-desktop	Uses same MCP registry as CLI
OpenCode	Global config (~/.config/opencode/opencode.json)	--tool opencode	Auto-updated by installer
Gemini	gemini mcp add	--tool gemini	User scope setup
Google Antigravity	Gemini-compatible MCP flow	--tool antigravity	Uses Gemini MCP command path
GitHub Copilot	copilot or gh copilot session	--tool copilot	Interactive/session-based setup

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:

Flag	Command	When to use
--runtime node (default)	node dist/index.js	Local source build
--runtime npx	npx -y mcp-baepsae@latest	npm registry, no global install
--runtime bunx	bunx mcp-baepsae@latest	Bun users
--runtime global	mcp-baepsae	After npm install -g mcp-baepsae

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.

Simulator-scoped	macOS-scoped
sim_describe_ui	mac_describe_ui
sim_search_ui	mac_search_ui
sim_tap	mac_tap
sim_type_text	mac_type_text
sim_swipe	mac_swipe
sim_key	mac_key
sim_key_sequence	mac_key_sequence
sim_key_combo	mac_key_combo
sim_touch	mac_touch
sim_right_click	mac_right_click
sim_scroll	mac_scroll
sim_drag_drop	mac_drag_drop
sim_list_windows	mac_list_windows
sim_activate_app	mac_activate_app
sim_screenshot_app	mac_screenshot_app

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

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" })

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.