> ## Documentation Index
> Fetch the complete documentation index at: https://docs.upsonic.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# OpenAI Chat

> Using OpenAI Chat Completions API with Upsonic

## Overview

OpenAI Chat Completions API provides access to GPT-4o, GPT-5, and other chat models. This is the standard API for conversational interactions.

**Model Class:** `OpenAIChatModel`

## Authentication

```bash theme={null}
export OPENAI_API_KEY="sk-..."
```

## Examples

```python theme={null}
from upsonic import Agent, Task
from upsonic.models.openai import OpenAIChatModel

model = OpenAIChatModel(model_name="gpt-4o")
agent = Agent(model=model)

task = Task("Hello, how are you?")
result = agent.do(task)
print(result)
```

## Model Settings

You can set model parameters in two ways: on the model or on the Agent.

**On the model:**

```python theme={null}
from upsonic import Agent, Task
from upsonic.models.openai import OpenAIChatModel, OpenAIChatModelSettings

model = OpenAIChatModel(
    model_name="gpt-4o-mini",
    settings=OpenAIChatModelSettings(max_tokens=1024, temperature=0.7)
)
agent = Agent(model=model)
```

**On the Agent (with model string or model instance):**

```python theme={null}
from upsonic import Agent, Task
from upsonic.models.openai import OpenAIChatModelSettings

agent = Agent(
    model="openai/gpt-4o-mini",
    settings=OpenAIChatModelSettings(max_tokens=1024, temperature=0.7)
)
```

## Parameters

| Parameter                 | Type                                          | Description                                 | Default        | Source   |
| ------------------------- | --------------------------------------------- | ------------------------------------------- | -------------- | -------- |
| `max_tokens`              | `int`                                         | Maximum tokens to generate                  | Model-specific | Base     |
| `temperature`             | `float`                                       | Sampling temperature (0.0-2.0)              | 1.0            | Base     |
| `top_p`                   | `float`                                       | Nucleus sampling threshold                  | 1.0            | Base     |
| `seed`                    | `int`                                         | Random seed for deterministic outputs       | None           | Base     |
| `stop_sequences`          | `list[str]`                                   | Sequences that stop generation              | None           | Base     |
| `presence_penalty`        | `float`                                       | Penalty for token presence (-2.0 to 2.0)    | 0.0            | Base     |
| `frequency_penalty`       | `float`                                       | Penalty for token frequency (-2.0 to 2.0)   | 0.0            | Base     |
| `logit_bias`              | `dict[str, int]`                              | Modify token likelihoods                    | None           | Base     |
| `parallel_tool_calls`     | `bool`                                        | Allow parallel tool calls                   | True           | Base     |
| `timeout`                 | `float`                                       | Request timeout in seconds                  | 600            | Base     |
| `extra_headers`           | `dict[str, str]`                              | Additional HTTP headers                     | None           | Base     |
| `extra_body`              | `object`                                      | Additional request body params              | None           | Base     |
| `openai_reasoning_effort` | `'low' \| 'medium' \| 'high'`                 | Computational effort for reasoning models   | None           | Specific |
| `openai_logprobs`         | `bool`                                        | Include log probabilities in response       | False          | Specific |
| `openai_top_logprobs`     | `int`                                         | Number of top log probs to return (1-20)    | None           | Specific |
| `openai_user`             | `str`                                         | Unique user identifier for abuse monitoring | None           | Specific |
| `openai_service_tier`     | `'auto' \| 'default' \| 'flex' \| 'priority'` | Service tier for request routing            | 'auto'         | Specific |
| `openai_prediction`       | `ChatCompletionPredictionContentParam`        | Enable predicted outputs                    | None           | Specific |