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

# GPT-5.5

> OpenAI's GPT-5.5 — flagship model for complex reasoning and professional work.

GPT-5.5 is available through Anyfast via the OpenAI Responses API (`/v1/responses`). It is OpenAI's most capable frontier model, designed for the most demanding professional and coding tasks.

## Key capabilities

* **Responses API** — Uses the newer `/v1/responses` endpoint with `input` instead of `messages`
* **Advanced reasoning** — Supports reasoning effort levels: none, low, medium (default), high, and xhigh
* **Verbosity control** — Set response verbosity to low, medium, or high
* **Streaming** — Supports real-time token streaming via SSE
* **Tool use** — Supports function calling, web search, file search, and computer use

## Quick example

<CodeGroup>
  ```bash cURL theme={null}
  curl https://www.anyfast.ai/v1/responses \
    -H "Authorization: Bearer YOUR_API_KEY" \
    -H "Content-Type: application/json" \
    -d '{
      "model": "gpt-5.5",
      "input": [
        { "role": "user", "content": "Explain quantum entanglement in simple terms." }
      ],
      "reasoning": {
        "effort": "high",
        "summary": "auto"
      },
      "text": {
        "format": { "type": "text" },
        "verbosity": "medium"
      },
      "store": true
    }'
  ```

  ```python Python theme={null}
  from openai import OpenAI

  client = OpenAI(
      api_key="YOUR_API_KEY",
      base_url="https://www.anyfast.ai/v1"
  )

  response = client.responses.create(
      model="gpt-5.5",
      input=[
          {"role": "user", "content": "Explain quantum entanglement in simple terms."}
      ],
      reasoning={"effort": "high", "summary": "auto"},
      text={"format": {"type": "text"}, "verbosity": "medium"},
      store=True
  )

  print(response.output[0].content[0].text)
  ```

  ```python Streaming theme={null}
  from openai import OpenAI

  client = OpenAI(
      api_key="YOUR_API_KEY",
      base_url="https://www.anyfast.ai/v1"
  )

  stream = client.responses.create(
      model="gpt-5.5",
      input=[
          {"role": "user", "content": "Write a short poem about the sea."}
      ],
      stream=True
  )

  for event in stream:
      if hasattr(event, 'delta'):
          print(event.delta, end="")
  ```
</CodeGroup>

## Parameters

| Parameter           | Type           | Required | Description                                                        |
| ------------------- | -------------- | -------- | ------------------------------------------------------------------ |
| `model`             | string         | Yes      | Must be `gpt-5.5`                                                  |
| `input`             | array          | Yes      | List of `{ role, content }` objects                                |
| `stream`            | boolean        | No       | Enable SSE streaming. Default: `false`                             |
| `temperature`       | float          | No       | `0`–2. Controls randomness. Default: `1`                           |
| `max_output_tokens` | integer        | No       | Maximum output tokens to generate. Minimum: `16`                   |
| `stop`              | string / array | No       | Sequences that stop generation                                     |
| `reasoning`         | object         | No       | `{ effort, summary }` — effort: none / low / medium / high / xhigh |
| `text`              | object         | No       | `{ format, verbosity }` — controls output format and verbosity     |
| `tools`             | array          | No       | List of tools the model may call                                   |
| `store`             | boolean        | No       | Store response for later retrieval. Default: `true`                |

<Card title="API Reference" icon="code" href="/api-reference/model-api/openai/gpt-5-5">
  View the interactive API playground for GPT-5.5.
</Card>

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