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Introduction

OpenAPI MCP Codegen is a CLI tool that parses OpenAPI 3.0/3.1 YAML specifications and generates a structured Quarkus-based SDK with MCP (Model Context Protocol) Toolset integration for AI/LLM agent usage.

Overview​

This tool automates the generation of:

  • Domain Layer: Data classes with Jackson/JSON-B annotations
  • Client Layer: REST client interfaces using MicroProfile Rest Client
  • MCP Tool Layer: Quarkus MCP server @Tool and @ToolArg annotated wrappers for AI/LLM integration

Why OpenAPI MCP Codegen?​

Type-Safe Generation​

Generate type-safe Kotlin code using KotlinPoet from your OpenAPI specifications. No more writing boilerplate code by hand.

MCP Integration​

Automatically generate Quarkus MCP tools that can be directly consumed by AI agents through the Model Context Protocol.

Ready to Build​

Each generated project includes a complete Gradle setup with all necessary dependencies, ready to compile and deploy.

Requirements​

  • JDK: 17 or higher
  • Gradle: 8 or higher
  • Input: OpenAPI 3.0 or 3.1 YAML specification

What Gets Generated?​

For a root package of io.swagger.petstore, the generator creates:

generated/
├── build.gradle.kts              # Gradle build configuration
├── settings.gradle.kts           # Gradle settings file
├── gradlew                       # Gradle wrapper script (Unix)
├── gradlew.bat                   # Gradle wrapper script (Windows)
├── gradle/
│   └── wrapper/
│       ├── gradle-wrapper.jar
│       └── gradle-wrapper.properties
├── src/main/kotlin/
│   └── io/swagger/petstore/
│       ├── domain/               # Data classes
│       │   ├── Pet.kt
│       │   ├── Category.kt
│       │   └── Order.kt
│       ├── client/               # REST client interface
│       │   └── PetstoreClient.kt
│       └── tool/                 # MCP tool wrappers
│           └── PetstoreTools.kt
└── src/main/resources/
    └── application.properties    # Quarkus configuration

Next Steps​