Xcode Development Skill

This skill provides guidance for using xc-mcp tools efficiently based on the task at hand. It routes operations to the appropriate MCP server or native CLI to minimize token overhead.

Server Architecture

The xc-mcp toolset is split into focused servers for token efficiency:

Server	Tools	Token Overhead	Use Case
xc-project	23	~5K	.xcodeproj file manipulation
xc-simulator	29	~6K	iOS Simulator, UI automation, sim logs
xc-device	12	~2K	Physical iOS devices
xc-debug	8	~2K	LLDB debugging
xc-swift	6	~1.5K	Swift Package Manager
xc-build	18	~3K	macOS builds, discovery, utilities
xc-mcp	89	~50K	All tools (monolithic)

Routing Guidelines

Project File Manipulation → xc-project MCP

Use mcp__xc-project__* tools for operations that modify .xcodeproj files:

• Adding/removing files, targets, groups
• Modifying build settings
• Managing Swift packages
• Adding frameworks and dependencies

These operations require the XcodeProj library - no CLI equivalent exists.

iOS Simulator Operations → xc-simulator MCP

Use mcp__xc-simulator__* tools for:

• Build and run workflows (build_run_sim)
• Simulator management (boot, list, erase)
• UI automation (tap, swipe, type text)
• Screenshot capture
• App installation and launch

Physical Device Operations → xc-device MCP

Use mcp__xc-device__* tools for:

• Building for devices
• Installing and launching apps on devices
• Device log capture

Debug Sessions → xc-debug MCP

Use mcp__xc-debug__* tools for:

• Attaching to running processes
• Setting/removing breakpoints
• Inspecting variables and stack
• Executing LLDB commands

Debug sessions maintain persistent state - use this server for multi-step debugging workflows.

Swift Packages → xc-swift MCP

Use mcp__xc-swift__* tools for:

• Building Swift packages
• Running tests
• Executing package binaries

macOS & Discovery → xc-build MCP

Use mcp__xc-build__* tools for:

• macOS application builds
• Project/scheme discovery
• Build settings queries
• Project scaffolding
• Clean operations

Simple Queries → Bash (Direct CLI)

For read-only queries, use Bash directly to avoid MCP overhead:

# List schemes
xcodebuild -list -json

# List simulators
xcrun simctl list devices --json

# Simple SPM build
swift build

Configuration Presets

Users can configure which servers to enable in their .mcp.json:

Minimal (project editing only) - ~5K tokens

{
  "mcpServers": {
    "xc-project": { "command": "xc-project" }
  }
}

Standard (build + project) - ~14K tokens

{
  "mcpServers": {
    "xc-project": { "command": "xc-project" },
    "xc-build": { "command": "xc-build" },
    "xc-simulator": { "command": "xc-simulator" }
  }
}

Full (all capabilities) - ~20K tokens

{
  "mcpServers": {
    "xc-project": { "command": "xc-project" },
    "xc-build": { "command": "xc-build" },
    "xc-simulator": { "command": "xc-simulator" },
    "xc-device": { "command": "xc-device" },
    "xc-debug": { "command": "xc-debug" },
    "xc-swift": { "command": "xc-swift" }
  }
}

Monolithic (all tools, single server) - ~50K tokens

{
  "mcpServers": {
    "xc-mcp": { "command": "xc-mcp" }
  }
}

Decision Matrix

Task	Recommended Approach
Edit .xcodeproj file	MCP xc-project
Build and run iOS app	MCP xc-simulator build_run_sim
Take screenshot	MCP xc-simulator screenshot
Debug crash	MCP xc-debug
Build Swift package	MCP xc-swift or Bash swift build
List schemes	Bash xcodebuild -list
Query build settings	Bash xcodebuild -showBuildSettings
Install on device	MCP xc-device

Fallback Behavior

If no MCP server is configured for a capability:

1. Attempt to use native CLI via Bash
2. For project file edits: suggest using xcodegen with spec files
3. Inform user about available MCP servers for better experience