> ## 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-6 Luna

> Use OpenAI GPT-6 Luna through AnyFast for focused, high-volume reasoning, vision, and structured-output workloads.

GPT-6 Luna is OpenAI's most efficient GPT-6 model for focused, high-volume tasks. Use the model ID `gpt-6-luna` with the OpenAI-compatible Responses API at `POST /v1/responses` or Chat Completions at `POST /v1/chat/completions`.

<Info>
  Prefer the Responses API for built-in tools, function calling with reasoning, image input, Structured Outputs, and prompt caching. Chat Completions function calling is supported only when `reasoning_effort` is `none`.
</Info>

## Model specifications

| Property                                | Value                                           |
| --------------------------------------- | ----------------------------------------------- |
| Model ID                                | `gpt-6-luna`                                    |
| Recommended API                         | Responses API                                   |
| Input                                   | Text and image                                  |
| Output                                  | Text                                            |
| Context window (official specification) | 1,050,000 tokens                                |
| Maximum output                          | 128,000 tokens                                  |
| Knowledge cutoff                        | May 18, 2026                                    |
| Reasoning effort                        | `none`, `low`, `medium`, `high`, `xhigh`, `max` |
| Default reasoning effort                | `medium`                                        |
| Fine-tuning                             | Not supported                                   |

## When to use GPT-6 Luna

* Focused, high-volume text processing
* Classification, extraction, and structured output
* Cost- and throughput-sensitive agent workflows
* Large-context summarization and analysis
* Vision tasks that combine text and image input
* Routine coding and automation tasks

## Quick start

<Tabs sync={false}>
  <Tab title="Responses API">
    ```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-6-luna",
        "input": "Classify this support ticket and return a short routing reason.",
        "reasoning": {
          "effort": "medium",
          "summary": "auto"
        },
        "max_output_tokens": 1024
      }'
    ```
  </Tab>

  <Tab title="Chat Completions">
    ```bash cURL theme={null}
    curl https://www.anyfast.ai/v1/chat/completions \
      -H "Authorization: Bearer YOUR_API_KEY" \
      -H "Content-Type: application/json" \
      -d '{
        "model": "gpt-6-luna",
        "messages": [
          { "role": "user", "content": "Summarize this incident report in three bullets." }
        ],
        "reasoning_effort": "medium",
        "max_completion_tokens": 1024
      }'
    ```
  </Tab>
</Tabs>

## Tool calling

Use the Responses API when the model needs to reason and call tools:

```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-6-luna",
    "input": "Look up the order status for order AF-1024.",
    "reasoning": { "effort": "medium" },
    "tools": [{
      "type": "function",
      "name": "get_order_status",
      "description": "Return the current status of an order.",
      "parameters": {
        "type": "object",
        "properties": {
          "order_id": { "type": "string" }
        },
        "required": ["order_id"],
        "additionalProperties": false
      },
      "strict": true
    }],
    "tool_choice": "auto"
  }'
```

<Warning>
  In Chat Completions, function calling requires `reasoning_effort: "none"`. Use the Responses API if you need tool calling with `low`, `medium`, `high`, `xhigh`, or `max` reasoning.
</Warning>

Chat Completions wraps each function definition inside a `function` object:

```json theme={null}
{
  "type": "function",
  "function": {
    "name": "get_order_status",
    "description": "Return the current status of an order.",
    "parameters": {
      "type": "object",
      "properties": {
        "order_id": { "type": "string" }
      },
      "required": ["order_id"],
      "additionalProperties": false
    },
    "strict": true
  }
}
```

### Built-in tools

OpenAI lists the following Responses API tools for GPT-6 Luna: Web search, File search, Image generation, Code Interpreter, Hosted shell, Apply patch, Skills, Computer use, MCP, and Tool search. Each tool has its own request fields and may require supporting resources such as files, vector stores, remote servers, or a computer-use loop.

## Reasoning and sampling rules

| Effort   | Typical use                                                             |
| -------- | ----------------------------------------------------------------------- |
| `none`   | Lowest latency, sampling controls, or Chat Completions function calling |
| `low`    | Routine tasks with light reasoning                                      |
| `medium` | General analysis and automation; the default                            |
| `high`   | Complex multi-step work                                                 |
| `xhigh`  | Difficult professional tasks                                            |
| `max`    | Maximum reasoning depth                                                 |

<Warning>
  When reasoning effort is not `none`, omit `temperature`, `top_p`, and `top_logprobs`. For Chat Completions, also omit `logprobs`. For Responses, do not request `message.output_text.logprobs` in `include`.
</Warning>

## Core parameters

| Parameter               | API              | Description                                                            |
| ----------------------- | ---------------- | ---------------------------------------------------------------------- |
| `model`                 | Both             | Must be `gpt-6-luna`                                                   |
| `input`                 | Responses        | Text or ordered input items                                            |
| `messages`              | Chat Completions | Ordered conversation messages                                          |
| `reasoning.effort`      | Responses        | `none`, `low`, `medium`, `high`, `xhigh`, or `max`                     |
| `reasoning_effort`      | Chat Completions | Same effort values as Responses                                        |
| `max_output_tokens`     | Responses        | Maximum visible output and reasoning tokens, up to 128,000             |
| `max_completion_tokens` | Chat Completions | Maximum completion and reasoning tokens                                |
| `tools`                 | Both             | Tool definitions; Chat Completions requires `reasoning_effort: "none"` |
| `text.format`           | Responses        | Text or strict JSON Schema output configuration                        |
| `stream`                | Both             | Stream response events                                                 |

<Note>
  In raw Responses API JSON, read generated text from message items in `output[].content[].text`. Some official SDKs expose an aggregated `output_text` convenience property, but clients should not require a top-level `output_text` field in the raw HTTP response.
</Note>

<Card title="API Reference" icon="code" href="/api-reference/model-api/openai/gpt-6-luna">
  View the GPT-6 Luna API reference.
</Card>

## Official references

* [GPT-6 Luna model page](https://developers.openai.com/api/docs/models/gpt-6-luna)
* [Using GPT-6](https://developers.openai.com/api/docs/guides/latest-model)

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