Building an MCP Server in Spring Boot (Step by Step) In the previous post, I explained what MCP is and why it matters. Now let's build one. I'll take my payment-service, a regular Spring Boot app with PostgreSQL and Kafka, and add an MCP server to it in about 30 minutes. By the end, the service will expose three tools that any AI agent can discover and call: getPaymentStatus , getRefundRate , and getFraudRiskScore . Starting Point My payment-service already has these Spring beans: @Service public class PaymentService { public Optional < Payment > findByTransactionId ( String txId ) { ... } public long count () { ... } public long countByStatus ( PaymentStatus status ) { ... } public List < Payment > findByStatusOrderByCreatedAtDesc ( PaymentStatus status ) { ... } } @Service public class FraudValidationService { public String calculateFraudScore ( double amount , String clientType , int hour , int orderCount , double successRate , int totalItems ) { ...…