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

# Chat completions

> Call /chat/completions with the Python SDK.

**Method**: `client.generate_text()` (stream with `client.stream_text()`).

### Example

```python theme={null}
chat = client.generate_text({
    "model": "openai/gpt-4o-mini",
    "messages": [
        {"role": "system", "content": "You are helpful."},
        {"role": "user", "content": "Write a limerick about lighthouses."},
    ],
    "temperature": 0.5,
})
```

### Streaming

```python theme={null}
for line in client.stream_text({
    "model": "openai/gpt-4o-mini",
    "messages": [{"role": "user", "content": "Stream a story"}],
}):
    print(line)
```

### Key parameters

* `model` (required): Target model id.
* `messages` (required): Ordered messages with roles `system|user|assistant|tool`; content as strings or parts.
* Sampling: `temperature` (0–2), `top_p` (0–1), `top_k` (>=1), `seed` (int, optional).
* Length/penalties: `max_output_tokens` (int), `presence_penalty` and `frequency_penalty` (-2 to 2), `stop` (string|string\[]).
* Tools: `tools` (definitions), `tool_choice` (auto/none/specific tool), `max_tool_calls` (int), `parallel_tool_calls` (bool).
* Logprobs: `logprobs` (bool), `top_logprobs` (0–20).
* Output: `response_format` (json/text), `metadata` (object passthrough), `stream` (bool), `service_tier`.
* Gateway extras: `usage` (bool to request usage), `meta` (bool to include meta block).

### Returns

`ChatCompletionsResponse`

```json theme={null}
{
  "id": "chatcmpl-123",
  "object": "chat.completion",
  "created": 1677652288,
  "model": "gpt-3.5-turbo-0125",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": "Hello there, how may I assist you today?"
      },
      "finish_reason": "stop"
    }
  ],
  "usage": {
    "prompt_tokens": 9,
    "completion_tokens": 12,
    "total_tokens": 21
  }
}
```

Or SSE lines when streaming

```
data: {"id":"chatcmpl-123","object":"chat.completion.chunk","created":1677652288,"model":"gpt-3.5-turbo-0125","choices":[{"index":0,"delta":{"role":"assistant","content":""},"finish_reason":null}]}

data: {"id":"chatcmpl-123","object":"chat.completion.chunk","created":1677652288,"model":"gpt-3.5-turbo-0125","choices":[{"index":0,"delta":{"content":"Hello"},"finish_reason":null}]}

data: {"id":"chatcmpl-123","object":"chat.completion.chunk","created":1677652288,"model":"gpt-3.5-turbo-0125","choices":[{"index":0,"delta":{},"finish_reason":"stop"}],"usage":{"prompt_tokens":9,"completion_tokens":12,"total_tokens":21}}

data: [DONE]
```