[REQ] New generator type for MCP server generation

[StephenFlavin]

Is your feature request related to a problem? Please describe.

I have OpenAPI specs for my APIs, but to use them with AI tools (Claude, ChatGPT, etc.) I need to manually write MCP servers. This means duplicating all my API definitions and maintaining two codebases.

Describe the solution you'd like

Add a Spring Boot MCP Server generator to OpenAPI Generator.

Input: My existing OpenAPI spec
Output: A working Spring Boot MCP server that AI tools can connect to

Example - from this OpenAPI operation:

/pets:
  get:
    summary: List all pets
    parameters:
      - name: limit
        in: query
        schema:
          type: integer

Generate this Spring Boot code:

@Service
public class PetStoreService {
    
    @McpTool(name = "list_pets", description = "List all pets")
    public List<Pet> listPets(
        @McpToolParam(description = "Maximum number of pets to return") Integer limit
    ) {
        // Call my existing API
        return restTemplate.getForObject("/pets?limit=" + limit, Pet[].class);
    }
}

@Configuration  
public class McpConfig {
    @Bean
    public ToolCallbackProvider tools(PetStoreService service) {
        return MethodToolCallbackProvider.from(service);
    }
}

Then I can connect Claude Desktop or VS Code to my API with zero manual work.

Describe alternatives you've considered

• Manual coding: Writing all the @McpTool methods by hand (tedious and error-prone)
• custom generator: write one myself
• existing implementations: e.g. harsha-iiiv/openapi-mcp-generator OR rmcp-openapi

Additional context

MCP (Model Context Protocol) is how AI tools connect to external APIs. Spring Boot already has full MCP support through Spring AI. This generator would just convert OpenAPI specs into the Spring Boot MCP format automatically.

Every popular language probably needs this - I'm focusing on Spring Boot because that's what I use, but Python/FastAPI, Node.js, etc. would benefit too.

[wing328]

thanks for the suggestion

cc @cachescrubber (2022/02) @welshm (2022/02) @MelleD (2022/02) @atextor (2022/02) @manedev79 (2022/02) @javisst (2022/02) @borsch (2022/02) @banlevente (2022/02) @Zomzog (2022/09) @martin-mfg (2023/08)

[wing328]

MCP (Model Context Protocol) is how AI tools connect to external APIs. Spring Boot already has full MCP support through Spring AI. This generator would just convert OpenAPI specs into the Spring Boot MCP format automatically.

we do have a spring boot generator. would that be a good starting point?

https://openapi-generator.tech/docs/generators/spring/

(library: spring-boot)

[StephenFlavin]

MCP (Model Context Protocol) is how AI tools connect to external APIs. Spring Boot already has full MCP support through Spring AI. This generator would just convert OpenAPI specs into the Spring Boot MCP format automatically.

we do have a spring boot generator. would that be a good starting point?

https://openapi-generator.tech/docs/generators/spring/

(library: spring-boot)

At the moment these generators are for server and client implementations, what I'm talking about is a little different...

MCP tells an LLM how it can interact with an internal API, from my perspective I've already written the docs MCP just needs to translate them which is what the tolls I've mentioned do.

MCP servers should be standalone, separated for the API the docs are for.

In my case I have an API, which uses openapi-generator and I'll be creating an MCP server generated from the same docs to run in a sidecar for AI chat clients to interface with, it would just be nice if that came from the official source.

[StephenFlavin]

This would be a new category of generator MCP

[wing328]

As you pointed out: Spring Boot already has full MCP support through Spring AI., my guess is that by enabling Spring AI in the auto-generated Spring boot sever, it would be pretty close to what you're looking for, right?

[StephenFlavin]

You could add the MCP tools there but from an architecture stand point I don't think you generally want your application server to be so tightly coupled with the MCP server. reading

Sorry if I'm misunderstanding

[wing328]

To be clear, I'm totally fine adding another generator for MCP server, e.g. cloning the spring generator to start with.

Just sharing what we've built so far to put us on the same page.

[StephenFlavin]

Right yes, much of the boiler plate bits will have similar patterns just new imports etc, only thing here is I would expect the output to be runnable so there's dependencies maven/gradle etc

[thibautrety]

Hello, I have the same need but in a quarkus environment. I have just created a Pull request here :
#22197
Besides, I have created an example project here :
https://github.com/thibautrety/quarkus_mcp

I hope this can help

[cjavdev]

Stainless has an MCP server generator that takes OpenAPI and converts into really nice MCP servers that work in code-mode which we've found is a much better approach than 1:1 mapping between endpoints and tools and even better than dynamic tools. Happy to chat if it's useful.