docs/source/en/reference/models.mdx

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# Models

<Tip warning={true}>

Smolagents is an experimental API which is subject to change at any time. Results returned by the agents
can vary as the APIs or underlying models are prone to change.

</Tip>

To learn more about agents and tools make sure to read the [introductory guide](../index). This page
contains the API docs for the underlying classes.

## Models

You're free to create and use your own models to power your agent.

You could use any `model` callable for your agent, as long as:
1. It follows the [messages format](./chat_templating) (`List[Dict[str, str]]`) for its input `messages`, and it returns a `str`.
2. It stops generating outputs *before* the sequences passed in the argument `stop_sequences`

For defining your LLM, you can make a `custom_model` method which accepts a list of [messages](./chat_templating) and returns an object with a .content attribute containing the text. This callable also needs to accept a `stop_sequences` argument that indicates when to stop generating.

```python
from huggingface_hub import login, InferenceClient

login("<YOUR_HUGGINGFACEHUB_API_TOKEN>")

model_id = "meta-llama/Llama-3.3-70B-Instruct"

client = InferenceClient(model=model_id)

def custom_model(messages, stop_sequences=["Task"]):
    response = client.chat_completion(messages, stop=stop_sequences, max_tokens=1000)
    answer = response.choices[0].message
    return answer
```

Additionally, `custom_model` can also take a `grammar` argument. In the case where you specify a `grammar` upon agent initialization, this argument will be passed to the calls to model, with the `grammar` that you defined upon initialization, to allow [constrained generation](https://huggingface.co/docs/text-generation-inference/conceptual/guidance) in order to force properly-formatted agent outputs.

### TransformersModel

For convenience, we have added a `TransformersModel` that implements the points above by building a local `transformers` pipeline for the model_id given at initialization.

```python
from smolagents import TransformersModel

model = TransformersModel(model_id="HuggingFaceTB/SmolLM-135M-Instruct")

print(model([{"role": "user", "content": [{"type": "text", "text": "Ok!"}]}], stop_sequences=["great"]))
```
```text
>>> What a
```

> [!TIP]
> You must have `transformers` and `torch` installed on your machine. Please run `pip install smolagents[transformers]` if it's not the case.

[[autodoc]] TransformersModel

### HfApiModel

The `HfApiModel` wraps huggingface_hub's [InferenceClient](https://huggingface.co/docs/huggingface_hub/main/en/guides/inference) for the execution of the LLM. It supports both HF's own [Inference API](https://huggingface.co/docs/api-inference/index) as well as all [Inference Providers](https://huggingface.co/blog/inference-providers) available on the Hub.

```python
from smolagents import HfApiModel

messages = [
  {"role": "user", "content": [{"type": "text", "text": "Hello, how are you?"}]}
]

model = HfApiModel()
print(model(messages))
```
```text
>>> Of course! If you change your mind, feel free to reach out. Take care!
```
[[autodoc]] HfApiModel

### LiteLLMModel

The `LiteLLMModel` leverages [LiteLLM](https://www.litellm.ai/) to support 100+ LLMs from various providers.
You can pass kwargs upon model initialization that will then be used whenever using the model, for instance below we pass `temperature`.

```python
from smolagents import LiteLLMModel

messages = [
  {"role": "user", "content": [{"type": "text", "text": "Hello, how are you?"}]}
]

model = LiteLLMModel("anthropic/claude-3-5-sonnet-latest", temperature=0.2, max_tokens=10)
print(model(messages))
```

[[autodoc]] LiteLLMModel

### OpenAIServerModel

This class lets you call any OpenAIServer compatible model.
Here's how you can set it (you can customise the `api_base` url to point to another server):
```py
import os
from smolagents import OpenAIServerModel

model = OpenAIServerModel(
    model_id="gpt-4o",
    api_base="https://api.openai.com/v1",
    api_key=os.environ["OPENAI_API_KEY"],
)
```

[[autodoc]] OpenAIServerModel

### AzureOpenAIServerModel

`AzureOpenAIServerModel` allows you to connect to any Azure OpenAI deployment. 

Below you can find an example of how to set it up, note that you can omit the `azure_endpoint`, `api_key`, and `api_version` arguments, provided you've set the corresponding environment variables -- `AZURE_OPENAI_ENDPOINT`, `AZURE_OPENAI_API_KEY`, and `OPENAI_API_VERSION`.

Pay attention to the lack of an `AZURE_` prefix for `OPENAI_API_VERSION`, this is due to the way the underlying [openai](https://github.com/openai/openai-python) package is designed. 

```py
import os

from smolagents import AzureOpenAIServerModel

model = AzureOpenAIServerModel(
    model_id = os.environ.get("AZURE_OPENAI_MODEL"),
    azure_endpoint=os.environ.get("AZURE_OPENAI_ENDPOINT"),
    api_key=os.environ.get("AZURE_OPENAI_API_KEY"),
    api_version=os.environ.get("OPENAI_API_VERSION")    
)
```

[[autodoc]] AzureOpenAIServerModel

### MLXModel


```python
from smolagents import MLXModel

model = MLXModel(model_id="HuggingFaceTB/SmolLM-135M-Instruct")

print(model([{"role": "user", "content": "Ok!"}], stop_sequences=["great"]))
```
```text
>>> What a
```

> [!TIP]
> You must have `mlx-lm` installed on your machine. Please run `pip install smolagents[mlx-lm]` if it's not the case.

[[autodoc]] MLXModel