MCP Server SDK Usage

MCP Server SDK Setup

Add this dependency to build MCP servers:

<dependency>
    <groupId>com.ajaxjs</groupId>
    <artifactId>aj-mcp-server</artifactId>
    <version>1.2</version>
</dependency>

We can find the latest version:

The server module includes:

• McpServer core processing engine
• FeatureMgr for annotation-based feature discovery
• @Tool, @Resource, @Prompt annotations
• Transport implementations for HTTP/SSE and Stdio

Creating a Server

To create an MCP server, you need to:

1. Define Service Classes: Create classes annotated with @McpService
2. Annotate Methods: Use @Tool, @Prompt, or @Resource annotations
3. Initialize Feature Manager: Scan packages for annotations
4. Configure Transport: Set up HTTP/SSE or Stdio transport, and some details of server
5. Start Server: Call server.start()

Creating MCP Service Class

AJ-MCP automatically discovers, registers, and manages MCP features (tools, resources, and prompts) through annotation-based scanning. This system enables developers to expose functionality simply by annotating methods with @Tool, @Resource, or @Prompt annotations within classes marked with @McpService.

@McpService
public class MyServerFeatures {
    @Tool(description = "Echoes a string")
    public String echoString(@ToolArg(description = "Input string") String input) {
        return input;
    }

    @Prompt(description = "Basic greeting prompt")
    public PromptMessage greeting(@PromptArg(description = "Name") String name) {
        PromptMessage message = new PromptMessage();
        message.setRole(Role.USER);
        message.setContent(new ContentText("Hello " + name));
        return message;
    }
}

Server Feature Management

The Feature Management system operates through a centralized FeatureMgr class that coordinates package scanning, annotation processing, and feature storage.The system uses reflection to discover annotated methods and stores feature metadata in concurrent hash maps for thread-safe runtime access.

Annotation System

The annotation system is built around several key annotations that mark classes and methods for MCP exposure:

Server configuration includes annotation-driven feature discovery through FeatureMgr.init() with package scanning FeatureMgr. This automatically discovers and registers @McpService annotated classes containing @Tool, @Resource, and @Prompt methods.

Initialize Feature Manager

The FeatureMgr.init() method orchestrates the entire annotation discovery process. It begins by scanning specified packages for classes annotated with @McpService.

FeatureMgr mgr=new FeatureMgr();
        mgr.init("com.foo.myproduct");.

Server Configuration

After feature manager initialization with package scanning, we can configure the server with:

• Server instance creation with transport layer setup
• Server configuration with name and version
• Connection timeout settings
• The page size for paginated responses

Server configuration is handled through the ServerConfig class, which contains essential server metadata McpServerInitialize. The configuration includes server name, version, and supported protocol versions McpServerInitialize.

During initialization, the server processes protocol version negotiation where it responds with the highest supported version or matches the client's requested version if supported McpServerInitialize.

FeatureMgr mgr=new FeatureMgr();
        mgr.init("com.foo.myproduct");

        McpServer server = new McpServer();
        server.setTransport(new ServerStdio(server));

        ServerConfig serverConfig = new ServerConfig();
        serverConfig.setName("MY_MCP_Server");
        serverConfig.setVersion("1.0");
        serverConfig.setPageSize(8);
        server.setServerConfig(serverConfig);