Spring AI - MCP Starter not working with starter-web and webflux and lazy initialization=true

[vaibhav-v-verma]

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Bug description

We are trying to implement the MCP Server using the spring-ai-starter-mcp-server-webmvc dependency in a Spring Boot application that includes both spring-boot-starter-web and spring-boot-starter-webflux. Our goal is to register tools via @Tool annotations and expose MCP endpoints (e.g., /mcp, /sse) as configured in application.yml.

However, during runtime:

• There are no logs indicating that tools were registered or capabilities enabled by the MCP server.

• When we attempt to hit the /mcp or /sse endpoints via Postman or curl, the application returns:

  No static resource found for /mcp
  

  or a 404 Not Found.

It appears the MCP server is not fully initializing or exposing the defined endpoints under this setup.

---

Environment

Component	Value
Spring Boot	3.2.x
Spring AI	1.0.0
MCP Starter	spring-ai-starter-mcp-server-webmvc
Java	17
Web dependencies	Both spring-boot-starter-web and spring-boot-starter-webflux are on classpath
Lazy Init	spring.main.lazy-initialization=true
Model	echo
Mode	SYNC

---

Steps to reproduce

1. Create a Spring Boot app with both starter-web and starter-webflux

2. Add spring-ai-starter-mcp-server-webmvc as a dependency

3. Add a @Tool-annotated class and register it via a ToolCallbackProvider bean

4. Enable MCP server in application.yml with endpoints /mcp and /sse

5. Run the app

6. Observe:

   • No tool registration logs

   • No endpoint registration confirmation

7. Try calling /mcp or /sse via Postman or curl → receive 404

---

Expected behavior

• MCP Server logs should indicate that tools were registered and capabilities enabled (e.g., “Registered tools: X”)

• Endpoints /mcp and /sse (or /completions for SYNC mode) should be exposed and respond correctly

• /completions should accept standard payloads and return tool responses

---

Minimal Complete Reproducible example

@Component
@Lazy(false)
public class SampleTool {
    @Tool(name = "sayHello", description = "Greets user")
    public String sayHello(String name) {
        return "Hello, " + name;
    }
}

@Bean
@Lazy(false)
public ToolCallbackProvider toolCallbackProvider(SampleTool tool) {
    return MethodToolCallbackProvider.builder()
        .toolObjects(tool)
        .build();
}

spring:
  main:
    lazy-initialization: true
ai:

mcp:

server:

enabled: true

type: SYNC

model: echo

sse-endpoint: /sse

sse-message-endpoint: /mcp

curl -X POST http://localhost:8080/completions \
  -H "Content-Type: application/json" \
  -d '{ "prompt": "call tool sayHello with name MCP" }'

Expected: "Hello MCP"
Actual: 404 Not Found / "No static resource found for /completions"

---

[vaibhav-v-verma]

Hi @wilocu ,
What is the timeline for this fix to be available publicly ?
Also, how can we use this server when both spring-boot-starter-web and spring-boot-starter-webflux dependency ?
Does spring-ai support this ? if not then what are the timelines ?