SyncMcpToolCallback call fails with UnsupportedOperationException if ToolContext is set

[henningSaulCM]

Bug description
Integrating and calling an MCP Tool with an existing Spring AI application that uses a ToolContext will result in an UnsupportedOperationException.

Environment
Spring AI 1.0.0-M6

Steps to reproduce

1. Integrate https://github.com/modelcontextprotocol/servers/tree/main/src/everything into a Spring AI application using https://docs.spring.io/spring-ai/reference/api/mcp/mcp-client-boot-starter-docs.html
2. Set the ToolContext in your Spring AI application
3. Call one of the tools provided by the everything MCP server, e.g. printEnv
4. Observe "UnsupportedOperationException: Tool context is not supported!" for SyncMcpToolCallback

Exception is raised here:

spring-ai/spring-ai-core/src/main/java/org/springframework/ai/tool/ToolCallback.java

Line 57 in 2394ac8

throw new UnsupportedOperationException("Tool context is not supported!");

Expected behavior
The MCP printEnv tool is called, ignoring the ToolContext (assuming this concept is not supported in MCP).

[tzolov]

Thanks @henningSaulCM , I believe this is a know issue and should have been resolved by
the 82d98b6
Can you test with 1.0.0-SNAPSHOT please?

[tzolov]

Likely the same as #2337

[henningSaulCM]

Hi @tzolov, thanks for chiming in.

I just tried with 1.0.0-SNAPSHOT (spring-ai-core-1.0.0-20250307.123602-1325.jar) and it seems I'm still getting the UnsupportedOperationException.

Stacktrace (excerpt):

java.lang.UnsupportedOperationException: Tool context is not supported!
		at org.springframework.ai.tool.ToolCallback.call(ToolCallback.java:57)
		at org.springframework.ai.model.tool.DefaultToolCallingManager.executeToolCall(DefaultToolCallingManager.java:226)
		at org.springframework.ai.model.tool.DefaultToolCallingManager.executeToolCalls(DefaultToolCallingManager.java:138)
		at org.springframework.ai.openai.OpenAiChatModel.lambda$internalStream$10(OpenAiChatModel.java:442)
		at reactor.core.publisher.FluxFlatMap$FlatMapMain.onNext(FluxFlatMap.java:388)
		...

Any thoughts?

[tzolov]

@henningSaulCM I overlooked that AsyncMcpToolCallback and SyncMcpToolCallback don't implement String call(String toolInput, ToolContext tooContext).
I'm not sure how to map ToolContext to a general-purpose MCP Tool Call, as the context only makes sense within Spring AI Tool Calling.
Are you looking for MCP ToolContext support, or is the error happening because you're mixing MCP and Spring AI tools? If it's the latter, we could implement the method for both callback types by ignoring the toolContext. Would that work?

[henningSaulCM]

Hi @tzolov,

Are you looking for MCP ToolContext support, or is the error happening because you're mixing MCP and Spring AI tools? If it's the latter, we could implement the method for both callback types by ignoring the toolContext. Would that work?

Yes, this is happening because I was trying to integrate MCP tools with an existing Spring AI application that uses custom Spring AI tools and custom (non-empty) ToolContext. If MCP does not support a ToolContext (yet), ignoring the ToolContext for MCP Tool calls would be just fine IMHO to avoid the Exception.

#2432 looks good to me.
Thanks for your work on Spring AI and the quick turnaround for this particular issue.

Cheers