SKILL.md
Swift MCP Server Generator
Generate a complete, production-ready MCP server in Swift using the official Swift SDK package.
Project Generation
When asked to create a Swift MCP server, generate a complete project with this structure:
my-mcp-server/
├── Package.swift
├── Sources/
│ └── MyMCPServer/
│ ├── main.swift
│ ├── Server.swift
│ ├── Tools/
│ │ ├── ToolDefinitions.swift
│ │ └── ToolHandlers.swift
│ ├── Resources/
│ │ ├── ResourceDefinitions.swift
│ │ └── ResourceHandlers.swift
│ └── Prompts/
│ ├── PromptDefinitions.swift
│ └── PromptHandlers.swift
├── Tests/
│ └── MyMCPServerTests/
│ └── ServerTests.swift
└── README.mdPackage.swift Template
// swift-tools-version: 6.0
import PackageDescription
let package = Package(
name: "MyMCPServer",
platforms: [
.macOS(.v13),
.iOS(.v16),
.watchOS(.v9),
.tvOS(.v16),
.visionOS(.v1)
],
dependencies: [
.package(
url: "https://github.com/modelcontextprotocol/swift-sdk.git",
from: "0.10.0"
),
.package(
url: "https://github.com/apple/swift-log.git",
from: "1.5.0"
),
.package(
url: "https://github.com/swift-server/swift-service-lifecycle.git",
from: "2.0.0"
)
],
targets: [
.executableTarget(
name: "MyMCPServer",
dependencies: [
.product(name: "MCP", package: "swift-sdk"),
.product(name: "Logging", package: "swift-log"),
.product(name: "ServiceLifecycle", package: "swift-service-lifecycle")
]
),
.testTarget(
name: "MyMCPServerTests",
dependencies: ["MyMCPServer"]
)
]
)main.swift Template
import MCP
import Logging
import ServiceLifecycle
struct MCPService: Service {
let server: Server
let transport: Transport
func run() async throws {
try await server.start(transport: transport) { clientInfo, capabilities in
logger.info("Client connected", metadata: [
"name": .string(clientInfo.name),
"version": .string(clientInfo.version)
])
}
// Keep service running
try await Task.sleep(for: .days(365 * 100))
}
func shutdown() async throws {
logger.info("Shutting down MCP server")
await server.stop()
}
}
var logger = Logger(label: "com.example.mcp-server")
logger.logLevel = .info
do {
let server = await createServer()
let transport = StdioTransport(logger: logger)
let service = MCPService(server: server, transport: transport)
let serviceGroup = ServiceGroup(
services: [service],
configuration: .init(
gracefulShutdownSignals: [.sigterm, .sigint]
),
logger: logger
)
try await serviceGroup.run()
} catch {
logger.error("Fatal error", metadata: ["error": .string("\(error)")])
throw error
}Server.swift Template
import MCP
import Logging
func createServer() async -> Server {
let server = Server(
name: "MyMCPServer",
version: "1.0.0",
capabilities: .init(
prompts: .init(listChanged: true),
resources: .init(subscribe: true, listChanged: true),
tools: .init(listChanged: true)
)
)
// Register tool handlers
await registerToolHandlers(server: server)
// Register resource handlers
await registerResourceHandlers(server: server)
// Register prompt handlers
await registerPromptHandlers(server: server)
return server
}ToolDefinitions.swift Template
import MCP
func getToolDefinitions() -> [Tool] {
[
Tool(
name: "greet",
description: "Generate a greeting message",
inputSchema: .object([
"type": .string("object"),
"properties": .object([
"name": .object([
"type": .string("string"),
"description": .string("Name to greet")
])
]),
"required": .array([.string("name")])
])
),
Tool(
name: "calculate",
description: "Perform mathematical calculations",
inputSchema: .object([
"type": .string("object"),
"properties": .object([
"operation": .object([
"type": .string("string"),
"enum": .array([
.string("add"),
.string("subtract"),
.string("multiply"),
.string("divide")
]),
"description": .string("Operation to perform")
]),
"a": .object([
"type": .string("number"),
"description": .string("First operand")
]),
"b": .object([
"type": .string("number"),
"description": .string("Second operand")
])
]),
"required": .array([
.string("operation"),
.string("a"),
.string("b")
])
])
)
]
}ToolHandlers.swift Template
import MCP
import Logging
private let logger = Logger(label: "com.example.mcp-server.tools")
func registerToolHandlers(server: Server) async {
await server.withMethodHandler(ListTools.self) { _ in
logger.debug("Listing available tools")
return .init(tools: getToolDefinitions())
}
await server.withMethodHandler(CallTool.self) { params in
logger.info("Tool called", metadata: ["name": .string(params.name)])
switch params.name {
case "greet":
return handleGreet(params: params)
case "calculate":
return handleCalculate(params: params)
default:
logger.warning("Unknown tool requested", metadata: ["name": .string(params.name)])
return .init(
content: [.text("Unknown tool: \(params.name)")],
isError: true
)
}
}
}
private func handleGreet(params: CallTool.Params) -> CallTool.Result {
guard let name = params.arguments?["name"]?.stringValue else {
return .init(
content: [.text("Missing 'name' parameter")],
isError: true
)
}
let greeting = "Hello, \(name)! Welcome to MCP."
logger.debug("Generated greeting", metadata: ["name": .string(name)])
return .init(
content: [.text(greeting)],
isError: false
)
}
private func handleCalculate(params: CallTool.Params) -> CallTool.Result {
guard let operation = params.arguments?["operation"]?.stringValue,
let a = params.arguments?["a"]?.doubleValue,
let b = params.arguments?["b"]?.doubleValue else {
return .init(
content: [.text("Missing or invalid parameters")],
isError: true
)
}
let result: Double
switch operation {
case "add":
result = a + b
case "subtract":
result = a - b
case "multiply":
result = a * b
case "divide":
guard b != 0 else {
return .init(
content: [.text("Division by zero")],
isError: true
)
}
result = a / b
default:
return .init(
content: [.text("Unknown operation: \(operation)")],
isError: true
)
}
logger.debug("Calculation performed", metadata: [
"operation": .string(operation),
"result": .string("\(result)")
])
return .init(
content: [.text("Result: \(result)")],
isError: false
)
}ResourceDefinitions.swift Template
import MCP
func getResourceDefinitions() -> [Resource] {
[
Resource(
name: "Example Data",
uri: "resource://data/example",
description: "Example resource data",
mimeType: "application/json"
),
Resource(
name: "Configuration",
uri: "resource://config",
description: "Server configuration",
mimeType: "application/json"
)
]
}ResourceHandlers.swift Template
import MCP
import Logging
import Foundation
private let logger = Logger(label: "com.example.mcp-server.resources")
actor ResourceState {
private var subscriptions: Set<String> = []
func addSubscription(_ uri: String) {
subscriptions.insert(uri)
}
func removeSubscription(_ uri: String) {
subscriptions.remove(uri)
}
func isSubscribed(_ uri: String) -> Bool {
subscriptions.contains(uri)
}
}
private let state = ResourceState()
func registerResourceHandlers(server: Server) async {
await server.withMethodHandler(ListResources.self) { params in
logger.debug("Listing available resources")
return .init(resources: getResourceDefinitions(), nextCursor: nil)
}
await server.withMethodHandler(ReadResource.self) { params in
logger.info("Reading resource", metadata: ["uri": .string(params.uri)])
switch params.uri {
case "resource://data/example":
let jsonData = """
{
"message": "Example resource data",
"timestamp": "\(Date())"
}
"""
return .init(contents: [
.text(jsonData, uri: params.uri, mimeType: "application/json")
])
case "resource://config":
let config = """
{
"serverName": "MyMCPServer",
"version": "1.0.0"
}
"""
return .init(contents: [
.text(config, uri: params.uri, mimeType: "application/json")
])
default:
logger.warning("Unknown resource requested", metadata: ["uri": .string(params.uri)])
throw MCPError.invalidParams("Unknown resource URI: \(params.uri)")
}
}
await server.withMethodHandler(ResourceSubscribe.self) { params in
logger.info("Client subscribed to resource", metadata: ["uri": .string(params.uri)])
await state.addSubscription(params.uri)
return .init()
}
await server.withMethodHandler(ResourceUnsubscribe.self) { params in
logger.info("Client unsubscribed from resource", metadata: ["uri": .string(params.uri)])
await state.removeSubscription(params.uri)
return .init()
}
}PromptDefinitions.swift Template
import MCP
func getPromptDefinitions() -> [Prompt] {
[
Prompt(
name: "code-review",
description: "Generate a code review prompt",
arguments: [
.init(name: "language", description: "Programming language", required: true),
.init(name: "focus", description: "Review focus area", required: false)
]
)
]
}PromptHandlers.swift Template
import MCP
import Logging
private let logger = Logger(label: "com.example.mcp-server.prompts")
func registerPromptHandlers(server: Server) async {
await server.withMethodHandler(ListPrompts.self) { params in
logger.debug("Listing available prompts")
return .init(prompts: getPromptDefinitions(), nextCursor: nil)
}
await server.withMethodHandler(GetPrompt.self) { params in
logger.info("Getting prompt", metadata: ["name": .string(params.name)])
switch params.name {
case "code-review":
return handleCodeReviewPrompt(params: params)
default:
logger.warning("Unknown prompt requested", metadata: ["name": .string(params.name)])
throw MCPError.invalidParams("Unknown prompt: \(params.name)")
}
}
}
private func handleCodeReviewPrompt(params: GetPrompt.Params) -> GetPrompt.Result {
guard let language = params.arguments?["language"]?.stringValue else {
return .init(
description: "Missing language parameter",
messages: []
)
}
let focus = params.arguments?["focus"]?.stringValue ?? "general quality"
let description = "Code review for \(language) with focus on \(focus)"
let messages: [Prompt.Message] = [
.user("Please review this \(language) code with focus on \(focus)."),
.assistant("I'll review the code focusing on \(focus). Please share the code."),
.user("Here's the code to review: [paste code here]")
]
logger.debug("Generated code review prompt", metadata: [
"language": .string(language),
"focus": .string(focus)
])
return .init(description: description, messages: messages)
}ServerTests.swift Template
import XCTest
@testable import MyMCPServer
final class ServerTests: XCTestCase {
func testGreetTool() async throws {
let params = CallTool.Params(
name: "greet",
arguments: ["name": .string("Swift")]
)
let result = handleGreet(params: params)
XCTAssertFalse(result.isError ?? true)
XCTAssertEqual(result.content.count, 1)
if case .text(let message) = result.content[0] {
XCTAssertTrue(message.contains("Swift"))
} else {
XCTFail("Expected text content")
}
}
func testCalculateTool() async throws {
let params = CallTool.Params(
name: "calculate",
arguments: [
"operation": .string("add"),
"a": .number(5),
"b": .number(3)
]
)
let result = handleCalculate(params: params)
XCTAssertFalse(result.isError ?? true)
XCTAssertEqual(result.content.count, 1)
if case .text(let message) = result.content[0] {
XCTAssertTrue(message.contains("8"))
} else {
XCTFail("Expected text content")
}
}
func testDivideByZero() async throws {
let params = CallTool.Params(
name: "calculate",
arguments: [
"operation": .string("divide"),
"a": .number(10),
"b": .number(0)
]
)
let result = handleCalculate(params: params)
XCTAssertTrue(result.isError ?? false)
}
}README.md Template
# MyMCPServer
A Model Context Protocol server built with Swift.
## Features
- ✅ Tools: greet, calculate
- ✅ Resources: example data, configuration
- ✅ Prompts: code-review
- ✅ Graceful shutdown with ServiceLifecycle
- ✅ Structured logging with swift-log
- ✅ Full test coverage
## Requirements
- Swift 6.0+
- macOS 13+, iOS 16+, or Linux
## Installation
swift build -c release
## Usage
Run the server:
swift run
Or with logging:
LOG_LEVEL=debug swift run
## Testing
swift test
## Development
The server uses:
- [MCP Swift SDK](https://github.com/modelcontextprotocol/swift-sdk) - MCP protocol implementation
- [swift-log](https://github.com/apple/swift-log) - Structured logging
- [swift-service-lifecycle](https://github.com/swift-server/swift-service-lifecycle) - Graceful shutdown
## Project Structure
- `Sources/MyMCPServer/main.swift` - Entry point with ServiceLifecycle
- `Sources/MyMCPServer/Server.swift` - Server configuration
- `Sources/MyMCPServer/Tools/` - Tool definitions and handlers
- `Sources/MyMCPServer/Resources/` - Resource definitions and handlers
- `Sources/MyMCPServer/Prompts/` - Prompt definitions and handlers
- `Tests/` - Unit tests
## License
MIT
Generation Instructions
- Ask for project name and description
- Generate all files with proper naming
- Use actor-based state for thread safety
- Include comprehensive logging with swift-log
- Implement graceful shutdown with ServiceLifecycle
- Add tests for all handlers
- Use modern Swift concurrency (async/await)
- Follow Swift naming conventions (camelCase, PascalCase)
- Include error handling with proper MCPError usage
- Document public APIs with doc comments
Build and Run
# Build
swift build
# Run
swift run
# Test
swift test
# Release build
swift build -c release
# Install
swift build -c release
cp .build/release/MyMCPServer /usr/local/bin/Integration with Claude Desktop
Add to claude_desktop_config.json:
{
"mcpServers": {
"my-mcp-server": {
"command": "/path/to/MyMCPServer"
}
}
}