Using LiteLLM router (with fallback and retry/cooldown) in an Agent

[ootkin]

Describe the question

I would like to implement an Agent with a custom and strong retry mechanism with fallback to another llm model if something goes wrong.

LiteLLM implements a router to do that: https://docs.litellm.ai/docs/routing

However I cannot pass a Router instance to the model params of the Agent.

You Documentation says the we need to set the model to an instance of LitellmModel, but there is no way to specify a fallback strategy.

Is there a way to do that?

Debug information

• Agents SDK version: 0.0.17
• Python version: 3.12

Repro steps

from litellm.router import Router

router = Router(
    model_list=[
        {
            "model_name": "gemini-1.5-flash",
            "litellm_params": {"model": "gemini/gemini-1.5-flash"},
            "timeout": 120,
            "retries": 1,
        },
        {
            "model_name": "gemini-1.5-pro-latest",
            "litellm_params": {"model": "gemini/gemini-1.5-flash"},
            "timeout": 80,
        },
    ],
    fallbacks=[{"gemini-1.5-flash": ["gemini-1.5-pro-latest"]}],
)

agent = Agent(
    name="My Agent",
    instructions=",
    model=router, # cannot do that
)

Expected behavior

Have the possibility to pass a LiteLLM router or specify a fallback strategy for an Agent