An MCP (Model Context Protocol) server that provides Swift code intelligence to AI agents through SourceKit-LSP.

This MCP server exposes SourceKit-LSP functionality to AI agents, enabling them to:

• Navigate Swift code: Find definitions, references, and implementations
• Understand types: Get hover information with type details and documentation
• Search symbols: Find classes, methods, and properties across your project
• Check diagnostics: Access compiler errors and warnings

npm install -g @leftspin/mcp-sourcekit-lsp

npm install -g github:leftspin/mcp-sourcekit-lsp

git clone https://github.com/leftspin/mcp-sourcekit-lsp.git cd mcp-sourcekit-lsp npm install npm run build # Optional: Set up development notifications (see Development Environment below) cp .env.example .env # Edit .env with your notification credentials

Add this to your Claude Desktop configuration file:

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json Windows: %APPDATA%\Claude\claude_desktop_config.json

{ "mcpServers": { "sourcekit-lsp": { "command": "npx", "args": ["@leftspin/mcp-sourcekit-lsp"], "env": { "SOURCEKIT_LSP_PATH": "/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/sourcekit-lsp" } } } }

Add this server to Claude Code's MCP settings:

1. Open Claude Code settings: Cmd+, (macOS) or Ctrl+, (Windows/Linux)
2. Search for "MCP" or navigate to the MCP section
3. Add a new server configuration:

{ "name": "sourcekit-lsp", "command": "npx", "args": ["@leftspin/mcp-sourcekit-lsp"], "env": { "SOURCEKIT_LSP_PATH": "/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/sourcekit-lsp" } }

Or if installed globally:

{ "name": "sourcekit-lsp", "command": "mcp-sourcekit-lsp", "env": { "SOURCEKIT_LSP_PATH": "/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/sourcekit-lsp" } }

• SOURCEKIT_LSP_PATH (optional): Path to sourcekit-lsp binary. Defaults to sourcekit-lsp in PATH.
• SOURCEKIT_BUILD_ARGS (optional): Additional arguments for sourcekit-lsp (e.g., -Xswiftc -debug-info-format=dwarf).

If you're working with Xcode projects, you may need to specify build arguments:

export SOURCEKIT_BUILD_ARGS="-Xswiftc -sdk -Xswiftc /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk"

Find where a symbol is defined.

{ "file": "/path/to/file.swift", "line": 10, "column": 5 }

Get type information and documentation for a symbol.

{ "file": "/path/to/file.swift", "line": 10, "column": 5 }

Find all references to a symbol.

{ "file": "/path/to/file.swift", "line": 10, "column": 5 }

Search for symbols in the workspace.

{ "query": "MyClass" }

Get compiler diagnostics for a file.

{ "file": "/path/to/file.swift" }

Provides an overview of the Swift project structure, including all Swift files and their organization.

Shows the current build configuration and compiler settings.

• Node.js 16 or later
• SourceKit-LSP (comes with Xcode or Swift toolchain)
• A Swift project (Swift Package Manager or Xcode project)

# Install dependencies npm install # Build TypeScript npm run build # Watch mode for development npm run watch # Run tests npm test # Test with MCP Inspector npx @modelcontextprotocol/inspector

The project includes a notification system for development updates. To use it:

1. Create environment file:

   cp .env.example .env

2. Add your credentials to .env:

   # Pushover credentials for development notifications (optional) PUSHOVER_TOKEN=your_pushover_app_token PUSHOVER_USER=your_pushover_user_key

3. Get Pushover credentials (optional):

   • Sign up at pushover.net
   • Create an application to get your app token
   • Find your user key in your account settings

Note: The .env file is automatically ignored by git to keep your credentials secure. The notification system is entirely optional and only used for development convenience.

# Run all tests npm test # Run tests in watch mode npm run test:watch # Run tests with coverage npm run test:coverage

If the server can't find sourcekit-lsp, set the SOURCEKIT_LSP_PATH environment variable:

Common locations:

• Xcode: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/sourcekit-lsp
• Swift toolchain: /Library/Developer/Toolchains/swift-latest.xctoolchain/usr/bin/sourcekit-lsp
• Homebrew: /opt/homebrew/bin/sourcekit-lsp

Check if sourcekit-lsp is available:

which sourcekit-lsp # Or try running it directly sourcekit-lsp --help

1. Build your project first: SourceKit-LSP requires compilation information

   # For SPM projects swift build # For Xcode projects xcodebuild -project YourProject.xcodeproj -scheme YourScheme build

2. Check file paths: Ensure file paths are absolute and the files exist

3. Verify workspace: Run the MCP server from your project's root directory

• Diagnostics are sent asynchronously by SourceKit-LSP
• Files with no errors/warnings will return empty diagnostics
• Large projects may take longer to analyze

• SourceKit-LSP can be resource-intensive on large projects
• Consider using SOURCEKIT_BUILD_ARGS to limit scope if needed
• Close unused Xcode projects to free up SourceKit-LSP resources

This MCP server acts as a bridge between AI agents and SourceKit-LSP:

AI Agent <--[MCP]--> This Server <--[LSP]--> SourceKit-LSP <--> Swift Code 

• MCP Tools: Synchronous request/response for AI agents
• LSP Communication: Asynchronous notifications and requests
• Caching: Diagnostics and file state cached for immediate responses

MIT

Contributions welcome! Please:

1. Fork the repository
2. Create a feature branch
3. Add tests for new functionality
4. Ensure all tests pass (npm test)
5. Submit a pull request

See the engineering plan for implementation details.