MCP Swift Example Server

Basic Stdio Example

This is a basic example demonstrating how to create a simple server that communicates over standard input/output (stdio) using the Model Context Protocol Swift SDK. This setup is compatible with applications like Claude Desktop.

Features

This simple server demonstrates:

• Setting up a basic MCP server
• Defining and registering a custom tool (swift_echo)
• Handling ListTools and CallTool requests
• Using StdioTransport for communication
• Detailed logging to stderr

Getting Started

Running the Echo Server

1. Clone this repository:

git clone https://github.com/devyhan/mcp-swift-example-server.git
cd mcp-swift-example-server

2. Build the server:

swift build -c release

This will create the executable at .build/release/macros-mcp-example-server. Note the full path to this executable.

Configure Claude Desktop

To make this server available as a tool provider in Claude Desktop, you need to add it to your Claude Desktop configuration file (claude_desktop_config.json). The location of this file varies by operating system.

Add an entry like the following to the mcpServers object in your claude_desktop_config.json, replacing /PATH/TO/YOUR/SERVER/ with the actual absolute path to the repository directory on your system:

{
    "mcpServers": {
        // ... other servers maybe ...
        "swift_echo_example": {
            "command": "/PATH/TO/YOUR/SERVER/mcp-swift-example-server/.build/release/macros-mcp-example-server"
        }
        // ... other servers maybe ...
    }
}

• swift_echo_example: This is the name you'll refer to the server by within Claude Desktop (you can change this).
• command: This must be the absolute path to the compiled executable you built in the previous step.

Client Example

The Examples directory contains a simple client implementation that demonstrates how to communicate with the MCP server:

# First start the server in one terminal:
swift run

# Then in another terminal, run the client example:
cd Examples
swift SimpleClient.swift

Requirements

• macOS 13 or later
• Swift 5.9 or later

Project Structure

• main.swift: Entry point for the server application
• MCPServer: MCP protocol server implementation
• EchoToolbox: Toolbox providing the basic echo tool

License

MIT

References

• MCP Specification
• Swift MCP SDK GitHub