> ## 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-5.6 Terra

> OpenAI GPT-5.6 Terra — balanced GPT-5.6 model for strong performance at a lower cost.

GPT-5.6 Terra is available through AnyFast via the OpenAI Responses API (`/v1/responses`). According to OpenAI's official model guidance, `gpt-5.6-terra` balances intelligence and cost within the GPT-5.6 family.

Use `gpt-5.6-terra` when you want strong GPT-5.6 reasoning, coding, and tool-use capability while keeping cost below the Sol tier.

## Key capabilities

* **Responses API** — Uses the newer `/v1/responses` endpoint with `input` instead of `messages`
* **Balanced tier** — GPT-5.6 model that balances intelligence and cost
* **Long context** — Supports a 1.05M token context window and up to 128K output tokens
* **Advanced reasoning** — Supports reasoning effort levels: none, low, medium (default), high, xhigh, and max
* **Pro mode** — Set `reasoning.mode` to `pro` for quality-first requests that can tolerate higher latency and token use
* **Persisted reasoning** — Use `reasoning.context` to control whether prior reasoning is reused across turns
* **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, code interpreter, computer use, and other Responses API tools
* **Programmatic Tool Calling** — Supports bounded tool-heavy workflows where the model can write JavaScript to coordinate eligible tools

## 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-5.6-terra",
      "input": [
        { "role": "user", "content": "Explain quantum entanglement in simple terms." }
      ],
      "reasoning": {
        "effort": "high",
        "summary": "auto",
        "context": "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-5.6-terra",
      input=[
          {"role": "user", "content": "Explain quantum entanglement in simple terms."}
      ],
      reasoning={"effort": "high", "summary": "auto", "context": "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-5.6-terra",
      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-5.6-terra`                                                                                                                                           |
| `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, mode, context }` — effort: none / low / medium / high / xhigh / max; mode can be `pro`; context can be `auto`, `all_turns`, or `current_turn` |
| `text`                 | object         | No       | `{ format, verbosity }` — controls output format and verbosity                                                                                                    |
| `tools`                | array          | No       | List of tools the model may call                                                                                                                                  |
| `prompt_cache_options` | object         | No       | Configure explicit prompt caching behavior when supported                                                                                                         |
| `safety_identifier`    | string         | No       | Stable privacy-preserving end-user identifier for safety systems                                                                                                  |
| `store`                | boolean        | No       | Store response for later retrieval. Default: `true`                                                                                                               |

<Card title="API Reference" icon="code" href="/api-reference/model-api/openai/gpt-5-6-terra">
  View the interactive API playground for GPT-5.6 Terra.
</Card>

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