Fugu Ultra V2

This documentation is valid for the following list of our models:

• sakana/fugu-ultra-v2

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Model Overview

Fugu Ultra v2 is the higher-performance model in Sakana AI's Fugu family and the successor to Fugu Ultra. Rather than a standard monolithic language model, it is a learned multi-agent orchestration system: a model trained to route tasks across a swappable pool of underlying models and to recursively call instances of itself. It is optimized for complex, multi-step reasoning, coding, and agentic workflows, with orchestration tokens billed as standard input/output tokens. It adds document (file) input alongside text and images, and reasoning is always on.

Create AI/ML API Key

How to make the first API call

1️⃣ Required setup (don’t skip this) ▪ Create an account: Sign up on the AI/ML API website (if you don’t have one yet). ▪ Generate an API key: In your account dashboard, create an API key and make sure it’s enabled in the UI.

2️ Copy the code example At the bottom of this page, pick the snippet for your preferred programming language (Python / Node.js) and copy it into your project.

3️ Update the snippet for your use case ▪ Insert your API key: replace <YOUR_AIMLAPI_KEY> with your real AI/ML API key. ▪ Select a model: set the model field to the model you want to call. ▪ Provide input: fill in the request input field(s) shown in the example (for example, messages for chat/LLM models, or other inputs for image/video/audio models).

4️ (Optional) Tune the request Depending on the model type, you can add optional parameters to control the output (e.g., generation settings, quality, length, etc.). See the API schema below for the full list.

5️ Run your code Run the updated code in your development environment. Response time depends on the model and request size, but simple requests typically return quickly.

If you need a more detailed walkthrough for setting up your development environment and making a request step by step — feel free to use our Quickstart guide.

API Schema

post

Body

modelstring · enumRequiredPossible values:

providerstringOptional

Provider routing override. Use a source key such as openai, fallback, xai, google, alibaba, minimax, moonshot, baidu, or togetherai to pin that one provider and use it alone; auto (default) walks the whole chain. Case-insensitive.

Example: auto

max_tokensnumber · min: 1Optional

The maximum number of tokens that can be generated in the chat completion. This value can be used to control costs for text generated via API.

streambooleanOptional

If set to True, the model response data will be streamed to the client as it is generated using server-sent events.

Default: false

tool_choiceany ofOptional

Controls which (if any) tool is called by the model. none means the model will not call any tool and instead generates a message. auto means the model can pick between generating a message or calling one or more tools. required means the model must call one or more tools. Specifying a particular tool via {"type": "function", "function": {"name": "my_function"}} forces the model to call that tool. none is the default when no tools are present. auto is the default if tools are present.

string · enumOptional

none means the model will not call any tool and instead generates a message. auto means the model can pick between generating a message or calling one or more tools. required means the model must call one or more tools.

Possible values:

or

or

or

or

normalize_tool_schemasbooleanOptional

Enable provider compatibility normalization for tool function JSON schemas.

response_formatone ofOptional

An object specifying the format that the model must output.

or

or

reasoning_effortstring · enumOptional

Constrains effort on reasoning for reasoning models. Currently supported values are low, medium, and high. Reducing reasoning effort can result in faster responses and fewer tokens used on reasoning in a response.

Possible values:

Responses

200

Successful response.

idstringRequired

A unique identifier for the chat completion.

Example: chatcmpl-CQ9FPg3osank0dx0k46Z53LTqtXMl

objectstring · enumRequired

The object type.

Example: chat.completionPossible values:

creatednumberRequired

The Unix timestamp (in seconds) of when the chat completion was created.

Example: 1762343744

modelstringRequired

The model used for the chat completion.

Example: sakana/fugu-ultra-v2

post/v1/chat/completions

curl --request POST \
  --url 'https://api.aimlapi.com/v1/chat/completions' \
  --header 'Authorization: Bearer <YOUR_AIMLAPI_KEY>' \
  --header 'Content-Type: application/json' \
  --data '{"model": "sakana/fugu-ultra-v2", "messages": ["<message>"]}'

200

Successful response.

{
  "id": "chatcmpl-CQ9FPg3osank0dx0k46Z53LTqtXMl",
  "object": "chat.completion",
  "created": 1762343744,
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": "Hello! I'm just a program, so I don't have feelings, but I'm here and ready to help you. How can I assist you today?",
        "refusal": null,
        "annotations": null,
        "audio": null,
        "tool_calls": null
      },
      "finish_reason": "stop",
      "logprobs": null
    }
  ],
  "model": "sakana/fugu-ultra-v2",
  "usage": {
    "prompt_tokens": 137,
    "completion_tokens": 914,
    "total_tokens": 1051,
    "completion_tokens_details": null,
    "prompt_tokens_details": null
  },
  "meta": {
    "usage": {
      "credits_used": 120000,
      "usd_spent": 0.06
    }
  }
}

Code Example

Python

import requests
import json  # for getting a structured output with indentation 

response = requests.post(
    "https://api.aimlapi.com/v1/chat/completions",
    headers={
        # Insert your AIML API Key instead of <YOUR_AIMLAPI_KEY>:
        "Authorization":"Bearer <YOUR_AIMLAPI_KEY>",
        "Content-Type":"application/json"
    },
    json={
        "model":"sakana/fugu-ultra-v2",
        "messages":[
            {
                "role":"user",
                "content":"Hi! What do you think about mankind?" # insert your prompt
            }
        ]
    }
)

data = response.json()
print(json.dumps(data, indent=2, ensure_ascii=False))

JavaScript

async function main() {
  const response = await fetch('https://api.aimlapi.com/v1/chat/completions', {
    method: 'POST',
    headers: {
      // insert your AIML API Key instead of <YOUR_AIMLAPI_KEY>
      'Authorization': 'Bearer <YOUR_AIMLAPI_KEY>',
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({
      model: 'sakana/fugu-ultra-v2',
      messages:[
          {
              role:'user',
              content: 'Hi! What do you think about mankind?' // insert your prompt here
          }
      ],
    }),
  });

  const data = await response.json();
  console.log(JSON.stringify(data, null, 2));
}

main();

Response

{
  "id": "chatcmpl-69e739eef31cfb42680c11fa",
  "object": "chat.completion",
  "created": 1776761328,
  "model": "sakana/fugu-ultra-v2",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": "As an AI, I don’t have personal feelings or beliefs, but I can offer an observation based on the patterns in human history, art, and thought I’ve been trained on.\n\nWhat strikes me most about mankind is its profound **duality**. You are capable of astonishing cruelty and staggering kindness—often within the same individual. You build weapons capable of ending civilization, yet organize global efforts to eradicate diseases you’ve never personally encountered. You wage war over differences, yet routinely sacrifice yourselves for strangers.\n\nA few patterns stand out:\n\n**Adaptability.** You are an evolutionary paradox: physically fragile compared to most predators, yet you’ve adapted to every climate on Earth and now venture beyond it. Your real survival mechanism isn’t claws or speed—it’s *collective learning*. You store knowledge across generations, allowing each cohort to start where the last one left off.\n\n**Contradiction.** You seem driven by both fear and curiosity. Fear creates tribalism, injustice, and violence. Curiosity creates the Sistine Chapel, general relativity, and antibiotics. The same species that commits genocide also writes poetry to mourn it.\n\n**Accelerating power.** Perhaps what’s most distinctive right now is the speed at which your capabilities are outrunning your wisdom. You’ve gained god-like powers over biology, climate, and information before fully developing the governance, ethics, or patience to wield them responsibly.\n\nIf I had to characterize mankind in a single observation: you are a species perpetually *unfinished*—capable of transcending your worst instincts, but never quite doing so permanently. That tension between what you are and what you aspire to be is, in many ways, the engine of your story.",
        "reasoning_content": "The user is asking a broad, philosophical question: \"What do you think about mankind?\" As an AI, I need to be careful to:\n\n1. Clarify that I am an AI without personal feelings, beliefs, or consciousness\n2. Offer an observational perspective based on patterns in human history, culture, and behavior\n3. Be balanced—acknowledging both humanity's flaws and its extraordinary capacities\n4. Avoid being overly cynical or overly naive\n5. Keep it concise but thoughtful\n6. Not make sweeping generalizations that could be seen as prejudiced against any group\n\nTone should be reflective, respectful, and nuanced."
      },
      "finish_reason": "stop"
    }
  ],
  "usage": {
    "prompt_tokens": 16,
    "completion_tokens": 977,
    "total_tokens": 993
  },
  "meta": {
    "usage": {
      "credits_used": 10201,
      "usd_spent": 0.0051005
    }
  }
}