Spring AI server.servlet.context-path not properly factoring into SSE MCP server path

Please do a quick search on GitHub issues first, there might be already a duplicate issue for the one you are about to create. If the bug is trivial, just go ahead and create the issue. Otherwise, please take a few moments and fill in the following sections:

Bug description When using the MCP Server Starter, one of the supported protocols is SSE. If you are setting a custom context path using the property server.servlet.context-path, the relevant paths for MCP will change, but the path given when you look at the /sse endpoint will not. Therefore MCP clients will break. This was tested with Cursor MCP.

Environment JVM: OpenJDK Runtime Environment Temurin-21.0.5+11 (build 21.0.5+11-LTS) Spring AI version: "1.0.0-M6" (Used BOM)

Application was written in Kotlin but that shouldn't be relevant here.

Steps to reproduce - Create any MCP server application that uses SSE - Connect it to an MCP client, should work fine (I used /sse as the path in Cursor) - Set the server.servlet.context-path, say to "/v1" - Attempt to update your setup in your MCP client, it will always fail

If you look at the output of the /sse endpoint, the reason is that the path provided by the endpoint is incorrect. It will match what you set in spring.ai.mcp.server.sse-message-endpoint but it will not include the context path.

Expected behavior In my opinion, this would be fixed if the endpoint that is returned in the call to the /sse endpoint also prepended the context path.

Minimal Complete Reproducible example Please provide a failing test or a minimal complete verifiable example that reproduces the issue. Bug reports that are reproducible will take priority in resolution over reports that are not reproducible.

Comment From: mlmw92

Same problem

Comment From: rod2k2

same problem, how to solve it if have to add server.servelt.context-path ?

Comment From: HollisChen1

I think there should be an issue of org.springframework.ai.mcp.server.autoconfigure.McpWebMvcServerAutoConfiguration(the same as McpWebFluxServerAutoConfiguration) by adding bean in our config class like below, using another constructor of WebMvcSseServerTransportProvider, make sure your servlet context path was added to spring.ai.mcp.server.base-url

@Bean
public WebMvcSseServerTransportProvider webMvcSseServerTransportProvider(
        ObjectProvider<ObjectMapper> objectMapperProvider, McpServerProperties serverProperties) {
    ObjectMapper objectMapper = objectMapperProvider.getIfAvailable(ObjectMapper::new);
    return new WebMvcSseServerTransportProvider(objectMapper,serverProperties.getBaseUrl(), serverProperties.getSseMessageEndpoint(), serverProperties.getSseEndpoint());
}


@Bean
public RouterFunction<ServerResponse> mvcMcpRouterFunction(WebMvcSseServerTransportProvider transportProvider) {
    return transportProvider.getRouterFunction();
}

Comment From: GregoireW

@HollisChen1 you mention:

make sure your servlet context path was added to spring.ai.mcp.server.base-url

But setting:

spring:
  ai:
    mcp:
      server:
        base-url: /myapp/
        sse-endpoint: /sse
        sse-message-endpoint: /mcp/message

on spring-ai 1.0.0-M7, I get on curl http://localhost:8080/sse a response containing: data:/mcp/message?sessio... so the base-url is not taken either I think

Comment From: GregoireW

I will answer myself: those beans are initialized with default configuration (base url and sseEndpoint (the /sse ) ) a small change to add the 2 others parameter should fix the issue

https://github.com/spring-projects/spring-ai/blob/687dea52e0ccf5ffe70dfbf6a7aa248d28c01bdc/auto-configurations/mcp/spring-ai-autoconfigure-mcp-server/src/main/java/org/springframework/ai/mcp/server/autoconfigure/McpWebMvcServerAutoConfiguration.java#L75

Comment From: GregoireW

looking for this issue, I found a related one: #2841

Comment From: weiwudu

@HollisChen1 you mention:

make sure your servlet context path was added to spring.ai.mcp.server.base-url

But setting:

spring: ai: mcp: server: base-url: /myapp/ sse-endpoint: /sse sse-message-endpoint: /mcp/message

on spring-ai 1.0.0-M7, I get on curl http://localhost:8080/sse a response containing: data:/mcp/message?sessio... so the base-url is not taken either I think

good job! This solution solved my problem

Comment From: mauricio1990silva

has this been fixed? My mcp data endpoint is still going after /mcp/message as supposed to /api/mcp/message even though I have the base-url set to /api/

spring-ai 1.0.0-M7