fugu-ultra
Fugu Ultra is the higher-performance tier of Sakana AI’s Fugu, a learned multi-agent orchestration system in which a trained language model routes work across other models.
Pricing: Input 1200 credits / 1M tokens (≈ $6.00), Output 7200 credits / 1M tokens (≈ $36.00).
Prices updated
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Fugu Ultra API on ModelFold
Fugu Ultra is the higher-performance tier of Sakana AI’s Fugu, a learned multi-agent orchestration system in which a trained language model routes work across other models. Try Fugu Ultra in the ModelFold Playground, then call it from your own code through an OpenAI-compatible chat completions API.
What Is the Fugu Ultra API
Fugu Ultra at a glance
Fugu Ultra is a chat model from Sakana AI. It accepts text and images as input and returns text, with a context window of up to 1M tokens.
Use it without hosting anything
On ModelFold you call Fugu Ultra with a single API key — no model weights to download and no inference servers to run. The same key also works for the other chat, image, video and audio models on ModelFold.
Core Capabilities of Fugu Ultra
Up to 1M tokens of context
Keep long conversations, large documents and sizeable code in a single request, so the model can reason over the full material instead of fragments.
Understands images
Besides text, Fugu Ultra accepts images as input, so a single request can combine instructions with visual or other media.
Function calling
Fugu Ultra supports tool (function) calling: describe your functions in the request and the model returns structured calls your code can run — the basis for agents and integrations.
Adjustable reasoning effort
Choose a reasoning effort level (low, medium or high) per request to balance depth of thinking against speed and token usage.
Structured outputs
Ask for JSON that follows a schema (response_format), which makes extraction, classification and system integrations more reliable.
How to Use Fugu Ultra on ModelFold
- 1
Step 1: Try it in the Playground
Open the Playground at the top of this page, type a prompt and see how Fugu Ultra responds before writing any code.
- 2
Step 2: Create an API key
Sign in to ModelFold and create an API key in the console. Keep it secret and send it as a Bearer token.
- 3
Step 3: Send a request
Call POST https://modelfold.ai/v1/chat/completions with "model": "fugu-ultra" and your messages. Existing OpenAI-compatible SDKs work by changing the base URL and key.
- ✓
Step 4: Ship and monitor
Integrate the response into your product and check token usage and spend for every call in the console logs.
What You Can Build with Fugu Ultra
Autonomous agents
Build agents that plan multi-step tasks, call your tools and APIs, and keep working toward a goal across long sessions.
Analysis and complex reasoning
Work through research questions, data interpretation, planning and other problems that need careful step-by-step reasoning.
AI coding assistants
Generate, explain, debug and refactor code, review pull requests and work through multi-file changes in developer tools and IDE plugins.
Screenshot and image understanding
Read screenshots, charts, diagrams and photos alongside text — for UI review, visual QA or turning images into structured data.
Frequently Asked Questions
What is Fugu Ultra?⌄
Fugu Ultra is the higher-performance tier of Sakana AI’s Fugu, a learned multi-agent orchestration system in which a trained language model routes work across other models.
Which inputs does Fugu Ultra support?⌄
Fugu Ultra accepts text and images and returns text. Through ModelFold you can send text and images (OpenAI-style image_url content); in the Playground you can also attach documents, which are converted to text.
How long is the context window of Fugu Ultra?⌄
Up to 1M tokens, shared between your input and the model’s output.
Does Fugu Ultra support function calling?⌄
Yes. Fugu Ultra supports tools / function calling through the standard tools parameter of the chat completions API.
How is Fugu Ultra billed on ModelFold?⌄
Pay as you go by tokens: input and output tokens are charged at the per-million-token prices shown on this page. There is no monthly fee, and failed requests are not charged.
How do I call Fugu Ultra through the API?⌄
Send a POST request to https://modelfold.ai/v1/chat/completions with "model": "fugu-ultra", using your ModelFold API key as the Bearer token.
| Input | 1200 credits 1M tokens≈ $6.00 |
| Output | 7200 credits 1M tokens≈ $36.00 |
Billed per token: input and output are priced separately, and thinking tokens count as output. The Playground charges exactly the same way.
Read API docs →AI Agents · Claude Code / Cursor / Trae →curl https://modelfold.ai/v1/chat/completions \
-H "Authorization: Bearer $MODELFOLD_API_KEY" \
-H "Content-Type: application/json" \
-d '{"model":"fugu-ultra","messages":[{"role":"user","content":"Hello"}]}'