Annotation-driven MCP Java SDK

🚀 Declarative MCP Java SDK Development with Java Annotations

This SDK is a lightweight, annotation-based framework that simplifies MCP server development in Java. Define, develop and integrate your MCP Resources / Prompts / Tools with minimal code - No Spring Framework Required.

📖 Documentation | 💡 Examples | 🐛 Report Issues

✨ Why Choose This SDK?

Key Advantages

• 🚫 No Spring Framework Required - Pure Java, lightweight and fast
• ⚡ Instant MCP Server - Get your server running with just 1 line of code
• 🎉 Zero Boilerplate - No need to write low-level MCP SDK code
• 👏 No JSON Schema - Forget about complex and lengthy JSON definitions
• 🎯 Focus on Logic - Concentrate on your core business logic
• 🔌 Spring AI Compatible - Configuration file compatible with Spring AI Framework
• 🌍 Multilingual Support - Built-in i18n support for MCP components
• 📦 Type-Safe - Leverage Java's type system for compile-time safety

Comparison with Official MCP Java SDK

🎯 Quick Start

Prerequisites

• Java 17 or later (required by official MCP Java SDK)
• Maven 3.6+ or Gradle 7+

5-Minutes Tutorial

Step 1: Add Dependency

Maven:

<dependency>
    <groupId>io.github.codeboyzhou</groupId>
    <artifactId>mcp-declarative-java-sdk</artifactId>
    <version>0.9.1</version>
</dependency>

Gradle:

implementation 'io.github.codeboyzhou:mcp-declarative-java-sdk:0.9.1'

Step 2: Create Your First MCP Server

@McpServerApplication
// If your MCP server components don't need to be multilingual, you can remove this annotation.
@McpI18nEnabled(resourceBundleBaseName = "i18n/mcp_server_components_info")
public class MyFirstMcpServer {
    public static void main(String[] args) {
        McpServers.run(MyFirstMcpServer.class, args)
            .startStdioServer(McpServerInfo.builder()
                .name("my-first-mcp-server")
                .version("1.0.0")
                .build());
    }
}

Step 3: Define MCP Resources (if needed)

public class MyResources {
    @McpResource(uri = "system://info", description = "System information")
    public Map<String, String> getSystemInfo() {
        Map<String, String> info = new HashMap<>();
        info.put("os", System.getProperty("os.name"));
        info.put("java", System.getProperty("java.version"));
        info.put("cores", String.valueOf(Runtime.getRuntime().availableProcessors()));
        return info;
    }
}

Step 4: Define MCP Tools

public class MyTools {
    @McpTool(description = "Calculate the sum of two numbers")
    public int add(
        @McpToolParam(name = "a", description = "First number", required = true) int a,
        @McpToolParam(name = "b", description = "Second number", required = true) int b
    ) {
        return a + b;
    }
}

Step 5: Define MCP Prompts (if needed)

public class MyPrompts {
    @McpPrompt(description = "Generate code for a given task")
    public String generateCode(
        @McpPromptParam(name = "language", description = "Programming language", required = true) String language,
        @McpPromptParam(name = "task", description = "Task description", required = true) String task
    ) {
        return String.format("Write %s code to: %s", language, task);
    }
}

Step 6: Run Your Server

# Compile and run
mvn clean package
java -jar target/your-app.jar

That's it! Your MCP server is now ready to serve resources, tools, and prompts!

📚 Core Concepts

What is MCP?

The Model Context Protocol (MCP) is a standardized protocol for building servers that expose data and functionality to LLM applications. Think of it like a web API, but specifically designed for LLM interactions.

MCP Components

Supported Server Modes

This SDK supports three MCP server modes:

1. STDIO - Standard input/output communication (default for CLI tools)
2. SSE (Server-Sent Events) - HTTP-based real-time communication
3. Streamable HTTP - HTTP streaming for web applications

🔧 Advanced Usage

Configuration File

Create mcp-server.yml in your classpath:

enabled: true
mode: STREAMABLE
name: my-mcp-server
version: 1.0.0
type: SYNC
request-timeout: 20000
capabilities:
  resource: true
  prompt: true
  tool: true
change-notification:
  resource: true
  prompt: true
  tool: true
streamable:
  mcp-endpoint: /mcp/message
  disallow-delete: true
  keep-alive-interval: 30000
  port: 8080

Then start your server:

McpServers servers = McpServers.run(MyMcpServer.class, args);
servers.startServer();  // Uses default mcp-server.yml
// or
servers.startServer("custom-config.yml");

Multilingual Support

Enable i18n for your MCP components:

@McpServerApplication
@McpI18nEnabled(resourceBundleBaseName = "messages")
public class I18nMcpServer {
    public static void main(String[] args) {
        McpServers.run(I18nMcpServer.class, args)
            .startStdioServer(McpServerInfo.builder()
                .name("i18n-server")
                .version("1.0.0")
                .build());
    }
}

// Create messages.properties
# messages.properties
tool.calculate.description=Calculate the sum of two numbers
tool.calculate.param.a.description=First number
tool.calculate.param.b.description=Second number

// Create messages_zh_CN.properties
# messages_zh_CN.properties
tool.calculate.description=计算两个数字的和
tool.calculate.param.a.description=第一个数字
tool.calculate.param.b.description=第二个数字

// Then use the i18n messages in your MCP components, like this:
@McpTool(description = "tool.calculate.description")
public int add(
    @McpToolParam(name = "a", description = "tool.calculate.param.a.description") int a,
    @McpToolParam(name = "b", description = "tool.calculate.param.b.description") int b
) {
    return a + b;
}

🏗️ Project Structure

A typical project structure:

your-mcp-project/
├── pom.xml
├── src/
│   ├── main/
│   │   ├── java/
│   │   │   └── com/
│   │   │       └── example/
│   │   │           ├── MyMcpServer.java          # Main entry point
│   │   │           ├── components/
│   │   │           │   ├── MyResources.java     # MCP Resources
│   │   │           │   ├── MyTools.java         # MCP Tools
│   │   │           │   └── MyPrompts.java       # MCP Prompts
│   │   │           └── service/
│   │   │               └── BusinessLogic.java    # Your business logic
│   │   └── resources/
│   │       ├── mcp-server.yml                    # MCP configuration
│   │       └── messages.properties               # i18n messages
│   └── test/
│       └── java/
│           └── com/
│               └── example/
│                   └── McpServerTest.java         # Unit tests

🧪 Testing

Run the test suite:

mvn test

Run tests with coverage:

mvn clean test jacoco:report

❓ FAQ

Q: Do I need Spring Framework?

A: No! This SDK is completely independent of Spring Framework. However, the configuration file format is compatible with Spring AI if you want to migrate.

Q: Can I use this in production?

A: This project is currently in active development. While it's stable for development and testing, we recommend thorough testing before production use.

Q: What Java version is required?

A: Java 17 or later is required, as this is a constraint of the underlying MCP Java SDK.

Q: How do I debug my MCP server?

A: You can use the inspector and set Java breakpoint to debug your MCP server.

🤝 Contributing

We welcome and appreciate contributions! Please follow these steps to contribute:

1. Fork the repository
2. Create a new branch for your feature or bug fix
3. Submit a pull request with a clear description of your changes

Development Setup

# Clone the repository
git clone https://github.com/codeboyzhou/mcp-declarative-java-sdk.git
cd mcp-declarative-java-sdk

# Build the project
mvn clean install

# Run tests
mvn test

📖 Documentation

• Official Documentation
• Examples Repository
• MCP Official Site

📄 License

This project is licensed under the MIT License.

🙏 Acknowledgments

• MCP Java SDK - The underlying MCP implementation
• Model Context Protocol - The protocol specification

[!NOTE] This project is under active development. We appreciate your feedback and contributions!