MCP Server using Spring Boot Java

A Model Context Protocol (MCP) server implementation built with Spring Boot and Java 21. This project demonstrates how to create an MCP server that provides user management tools for AI assistants.

Features

• Implements MCP server functionality using Spring AI
• Exposes user management tools via MCP
• Synchronous communication mode
• Support for Standard I/O and Server-Sent Events transports
• Integrates with DummyJSON external API for user data

Technologies

• Java 21
• Spring Boot 3.4.3
• Spring AI (Model Context Protocol)
• Project Lombok
• Maven

Getting Started

Prerequisites

• Java 21 or higher
• Maven

Installation

1. Clone the repository

git clone https://github.com/yourusername/mcp-spring-java.git
cd mcp-spring-java

2. Build the project

mvn clean package

3. Run the application

java -jar target/mcp-spring-java-0.0.1-SNAPSHOT.jar

Configuration

The MCP server is configured in application.yml:

• Server runs on port 8090
• Server name: my-dummy-users-server
• Synchronous communication mode
• Supports STDIO transport for terminal-based communication
• Exposes /mcp/message endpoint for SSE communication

Available Tools

The server exposes the following user management tools:

• getAllUsers - Get all users with pagination
• getAllUsersDefault - Get all users with default pagination
• getUserById - Get a single user by ID
• searchUsers - Search for users by query
• addUser - Add a new user
• updateUser - Update a user
• deleteUser - Delete a user

Testing with Postman

You can use Postman to test the MCP server endpoints:

1. Start the MCP server

2. Open Postman and create a new request:

   • Method: POST
   • URL: http://localhost:8090/mcp/message
   • Headers:
     • Content-Type: application/json
     • Accept: application/json

3. For the request body, use the following JSON format to invoke any of the available tools:

{
  "message": {
    "toolCalls": [
      {
        "id": "call-123",
        "name": "[TOOL_NAME]",
        "parameters": {
          "[PARAMETER_NAME]": "[PARAMETER_VALUE]"
        }
      }
    ]
  }
}

Example Requests

Get All Users (Default Pagination)

{
  "message": {
    "toolCalls": [
      {
        "id": "call-123",
        "name": "getAllUsersDefault",
        "parameters": {}
      }
    ]
  }
}

Get User by ID

{
  "message": {
    "toolCalls": [
      {
        "id": "call-123",
        "name": "getUserById",
        "parameters": {
          "id": 1
        }
      }
    ]
  }
}

Search Users

{
  "message": {
    "toolCalls": [
      {
        "id": "call-123",
        "name": "searchUsers",
        "parameters": {
          "query": "John"
        }
      }
    ]
  }
}

The response will contain a JSON object with the results from the tool execution.

Usage with MCP Clients