Yes it is. tool_choice=required tells the model it must use some tool, but leaves the specific tool up to the model. You could add more stuff to your prompt to guide the model, or use an input that clearly requires the MCP tool.

Also note that the MCP server tool is called as part of the model, so it will show up in the call to responses API in the tracing UI. (i.e. the row that says POST/v1/responses)

You need to check whether the message sent when calling the LLM API includes all of your tools. If it does, then there's no issue. Which tool gets selected depends on your prompt and the LLM's decision-making, not on the Agent SDK itself.

Thanks a lot. I found the reason. The prompt was not strong enough to make it use MCP tools.