Help in understanding Extended OpenAI Conversation "home control" commands

"Hello, I’m new to Home Assistant and the community.
I am trying to use the compatible OpenAI APIs from TogetherAI with the Extended OpenAI Conversation addon. The configuration went well (I think), the model via Assist answers general questions as “What’s the capital of France”, but if I ask it to control a device, for example, ‘turn on kitchen light,’ it responds with XML instead of executing the command. I am using the model meta-llama/Llama-3.3-70B-Instruct-Turbo.

Xml response:

<function=execute_services>{"list": [{"domain": "switch", "service": "turn_on", "service_data": {"entity_id": "switch.sonoff_xxxxxx"}}]}</function>

Can someone help me? Thank you."