Grok only works with tools

[filipre]

Hi!

It looks like, that Grok or openai.LLM.with_x_ai only works when at least one tool is passed to the provided agent (see example below). Otherwise I always get this error message

livekit.agents._exceptions.APIStatusError: Error code: 400 - {'code': 'Client specified an invalid argument', 'error': 'Invalid request content: A tool_choice was set on the request but no tools were specified.'} (status_code=400, request_id=None, body=Invalid request content: A tool_choice was set on the request but no tools were specified., retryable=True)

Am I doing something wrong or is this a bug? Thanks for the help!

Minimal Code Example

# imports ...

@function_tool
async def lookup_weather(
    context: RunContext,
    location: str,
):
    """Used to look up weather information."""

    return {"weather": "sunny", "temperature": 70}


async def entrypoint(ctx: JobContext):
    await ctx.connect()

    agent = Agent(
        instructions="You are a friendly voice assistant built by LiveKit.",
        tools=[lookup_weather], # <- always needs to be a non-empty list
    )
    stt = ...
    llm = openai.LLM.with_x_ai(
        model="grok-3-mini-fast",
        temperature=0.5,
        tool_choice="auto", # <- doesn't help
    )
    tts = ...
    session = AgentSession(
        stt=stt,
        llm=llm,
        tts=tts,
    )

    await session.start(agent=agent, room=ctx.room)
    await session.generate_reply(instructions="greet the user and ask about their day")


if __name__ == "__main__":
    cli.run_app(WorkerOptions(entrypoint_fnc=entrypoint))

Tests

Here is a test matrix

toolsArgument	tool_choice Argument	Result
[lookup_weather]	not given	✅ Agent uses tool
[lookup_weather]	auto	✅ Agent uses tool
[lookup_weather]	none	✅ Agent doesn't use tool
[]	not given	❌ 400 Error
[]	auto	❌ 400 Error
[]	none	❌ 400 Error
None	not given	❌ 400 Error
None	auto	❌ 400 Error
None	none	❌ 400 Error

Dependencies

➜  livekit-grok git:(main) ✗ uv pip freeze
aiofiles==24.1.0
aiohappyeyeballs==2.6.1
aiohttp==3.12.15
aiosignal==1.4.0
annotated-types==0.7.0
anyio==4.10.0
attrs==25.3.0
av==15.0.0
certifi==2025.8.3
cffi==1.17.1
charset-normalizer==3.4.2
click==8.2.1
colorama==0.4.6
distro==1.9.0
docstring-parser==0.17.0
eval-type-backport==0.2.2
frozenlist==1.7.0
googleapis-common-protos==1.70.0
grpcio==1.74.0
h11==0.16.0
httpcore==1.0.9
httpx==0.28.1
idna==3.10
importlib-metadata==8.7.0
jiter==0.10.0
livekit==1.0.12
livekit-agents==1.2.4
livekit-api==1.0.5
livekit-blingfire==1.0.0
livekit-plugins-openai==1.2.4
livekit-protocol==1.0.5
multidict==6.6.3
nest-asyncio==1.6.0
numpy==2.3.2
openai==1.99.4
opentelemetry-api==1.36.0
opentelemetry-exporter-otlp==1.36.0
opentelemetry-exporter-otlp-proto-common==1.36.0
opentelemetry-exporter-otlp-proto-grpc==1.36.0
opentelemetry-exporter-otlp-proto-http==1.36.0
opentelemetry-proto==1.36.0
opentelemetry-sdk==1.36.0
opentelemetry-semantic-conventions==0.57b0
pillow==11.3.0
prometheus-client==0.22.1
propcache==0.3.2
protobuf==6.31.1
psutil==7.0.0
pycparser==2.22
pydantic==2.11.7
pydantic-core==2.33.2
pyjwt==2.10.1
python-dotenv==1.1.1
requests==2.32.4
sniffio==1.3.1
sounddevice==0.5.2
tqdm==4.67.1
types-protobuf==4.25.0.20240417
typing-extensions==4.14.1
typing-inspection==0.4.1
urllib3==2.5.0
watchfiles==1.1.0
websockets==15.0.1
yarl==1.20.1
zipp==3.23.0

Related Issues

Possibly google/adk-python#952 but not sure

[longcw]

Thanks for reporting, should be fixed in #3126