mcp-server-with-spring-ai

mcp-server-with-spring-ai is a Spring Boot integrated MCP (Model Context Protocol) server example that showcases how to expose executable tools from an MCP server to clients (including LLMs) and how to wire a MCP client to consume those tools. The documentation explains MCP at a high level, outlines the three-layer MCP Java SDK architecture (Client/Server Layer, Session Layer, Transport Layer), and demonstrates two sample tools implemented in SellerAccountTools. This repo emphasizes how an MCP server can connect to external data sources (e.g., a PostgreSQL DB) and expose tools that an AI model can invoke to retrieve data, with the example illustrating tool invocation and automatic tool selection by prompts.

Use this MCP server to enable AI models (including LLMs) to interact with external data sources via well-defined tools exposed by the server. In the example, two tools are exposed to search a SellerAccounts table by name or by owner. The MCP architecture is described as three-layer: Client/Server Layer (McpClient and McpServer), Session Layer (McpSession with DefaultMcpSession), and Transport Layer (McpTransport for JSON-RPC with multiple transports). The server exposes tools that the client can invoke, allowing the LLM to select the correct tool based on the prompt.

Code example (as provided in the docs):

@Service
public class SellerAccountTools {
    private final SellerAccountRepository sellerAccountRepository;
    public SellerAccountTools(SellerAccountRepository sellerAccountRepository) {
        this.sellerAccountRepository = sellerAccountRepository;
    }
    @Tool(name = "Search Seller account by name", description = "Find all Seller Accounts by name")
    public String getAccountByName(
            @ToolParam(description = "Seller Account Name") String name) {
        List<SellerAccount> accountList = sellerAccountRepository.findByName(name);
        StringBuilder result = new StringBuilder();
        for (SellerAccount account : accountList) {
            result.append(account.toString()).append("\n");
        }
        return result.toString();
    }
    @Tool(description = "Find all Seller Accounts by owner")
    public String getAccountByOwner(
            @ToolParam(description = "Seller Account owner") String owner) {
        List<SellerAccount> accountList = sellerAccountRepository.findByOwner(owner);
        StringBuilder result = new StringBuilder();
        for (SellerAccount account : accountList) {
            result.append(account.toString()).append("\n");
        }
        return result.toString();
    }
}

Explanation