Fugu Ultra
Fugu Ultra is Sakana AI's quality-maximizing multi-agent system released June 21, 2026. Behind a single model API, Fugu Ultra coordinates a pool of expert agents to solve hard, multi-step problems. Available through AI Gateway with unified billing, observability, and provider routing.
View API reference- Input and output price
- Input $5, Output $30, Per 1M tokens
- 24h uptime
- Loading AI Gateway uptime
import { streamText } from 'ai'
const result = streamText({ model: 'sakana/fugu-ultra', prompt: 'Why is the sky blue?'})Copy link to headingPlayground
Try out Fugu Ultra by Sakana AI. Usage is billed to your team at API rates. Free users (those who haven't made a payment) get $5 of credits every 30 days.
Fugu Ultra
Fugu Ultra
Copy link to headingProviders
Route requests across multiple providers. Copy a provider slug to set your preference. Visit the docs for more info. Using a provider means you agree to their terms, listed under Legal.
Copy link to headingUptime24 hours
Direct request success rate on AI Gateway and per-provider. Visit the docs for more info.
Copy link to headingThroughput24 hours
P50 throughput on live AI Gateway traffic, in tokens per second (TPS). Visit the docs for more info.
Copy link to headingLatency24 hours
P50 time to first token (TTFT) on live AI Gateway traffic, in milliseconds. View the docs for more info.
Getting started
Call Fugu Ultra through AI Gateway with the AI SDK generateText and streamText functions, or through the OpenAI Chat Completions, OpenAI Responses, and Anthropic Messages APIs by changing the base URL. AI Gateway authenticates the request and routes it to an available provider.
Install the AI SDK (pnpm add ai dotenv), create an API key from the API Keys page, and set it as AI_GATEWAY_API_KEY in your environment. Full setup is covered in the text generation quickstart.
import { generateText } from 'ai';import 'dotenv/config';
async function main() { const result = await generateText({ model: 'sakana/fugu-ultra', prompt: 'Why is the sky blue?', });
console.log(result.text);}
main().catch(console.error);Top-level parameters
The same Fugu Ultra request in each API format AI Gateway supports.
import { generateText } from 'ai';import 'dotenv/config';
async function main() { const result = await generateText({ model: 'sakana/fugu-ultra', system: 'You are a concise technical assistant.', prompt: 'Summarize the tradeoffs between static generation and SSR.', maxOutputTokens: 1024, });
console.log(result.text);}
main().catch(console.error);Standard parameters like prompt, messages, temperature, and tools work as documented in the AI SDK docs. These are the parameters with model-specific behavior.
| Parameter | Type | Required | Description |
|---|---|---|---|
model | string | Yes | Model ID in the form creator/model, e.g. sakana/fugu-ultra. AI Gateway routes the request to an available provider. |
maxOutputTokens | number | No | Hard cap on generated tokens. Fugu Ultra supports up to 1,000,000 output tokens. Reasoning tokens count toward this limit. |
reasoning | 'provider-default' | 'none' | 'minimal' | 'low' | 'medium' | 'high' | 'xhigh' | No | Provider-agnostic reasoning effort, available in AI SDK 7 or later. Maps to the provider’s native reasoning configuration; reasoning settings under providerOptions take precedence when both are set. See the Reasoning section below. |
providerOptions | Record<string, JSONValue> | No | AI Gateway routing options under gateway, plus any provider-native options under the provider’s own namespace — see the table below. |
Input limits
| Input | Formats | Sources | Max count | Max size | Limits |
|---|---|---|---|---|---|
| Text | — | — | — | — | Prompt and response share the 1M-token context window |
| Image | — | URL, base64, Uint8Array | — | — | Sent as image parts in messages; counts as input tokens |
Provider options
Set AI Gateway routing options under providerOptions.gateway. For provider-specific options, pass them under the provider’s namespace as documented by the AI SDK.
Learn more in the AI SDK provider docs.
import { generateText } from 'ai';import 'dotenv/config';
async function main() { const result = await generateText({ model: 'sakana/fugu-ultra', prompt: 'Why is the sky blue?', providerOptions: { gateway: { only: ['sakana'], }, }, });
console.log(result.text);}
main().catch(console.error);These AI Gateway routing options apply to every model. Provider-specific options pass through under the provider’s own namespace (for example providerOptions.anthropic) exactly as documented by the AI SDK.
| Parameter | Type | Required | Description |
|---|---|---|---|
providerOptions.gateway.only | string[] | No | Restrict routing to these provider slugs. Requests fail over only within the listed providers. |
providerOptions.gateway.order | string[] | No | Preferred provider order. Listed providers are tried first; unlisted providers remain available as fallbacks. |
providerOptions.gateway.sort | 'cost' | 'ttft' | 'tps' | No | Rank candidate providers by price, time to first token, or tokens per second instead of the default routing order. |
providerOptions.gateway.zeroDataRetention | boolean | No | Route only to providers with a zero-data-retention policy for this model. |
Routing across providers
AI Gateway serves the same model through multiple providers and fails over automatically. order expresses a preference while keeping every provider eligible; only is a hard allowlist — if none of the listed providers are available the request fails instead of falling back.
Options under a provider's own namespace (for example providerOptions.anthropic) are forwarded to that provider with the request. Providers ignore option namespaces that don't apply to them, so it is safe to set provider options alongside gateway routing options.
Reasoning
AI Gateway bridges reasoning across every API format. The AI SDK exposes a provider-agnostic top-level reasoning level (none, minimal, low, medium, high, or xhigh); the Chat Completions and Responses formats take the same effort under reasoning.effort; and the Anthropic Messages format uses a native thinking token budget. Whichever you send, the gateway maps it to the target model’s native configuration, converting between effort levels and token budgets as needed. Reasoning-related settings under providerOptions take full precedence over the top-level reasoning value and are never merged. Reasoning tokens typically count toward your output-token usage, though how they’re reported and billed varies by provider.
Learn more in the AI Gateway reasoning guide.
import { generateText } from 'ai';import 'dotenv/config';
async function main() { const result = await generateText({ model: 'sakana/fugu-ultra', prompt: 'Explain the Monty Hall problem step by step.', reasoning: 'high', });
console.log(result.text);}
main().catch(console.error);Image input
Send images alongside text as message parts. Images count as input tokens.
import { generateText } from 'ai';import 'dotenv/config';
async function main() { const result = await generateText({ model: 'sakana/fugu-ultra', messages: [ { role: 'user', content: [ { type: 'text', text: 'Describe this image.' }, { type: 'image', image: 'https://example.com/photo.jpg' }, ], }, ], });
console.log(result.text);}
main().catch(console.error);Tool calling
Expose tools the model can call. Define each tool’s inputs with a Zod schema.
import { generateText, tool } from 'ai';import { z } from 'zod';import 'dotenv/config';
async function main() { const result = await generateText({ model: 'sakana/fugu-ultra', prompt: 'What is the weather in San Francisco?', tools: { getWeather: tool({ description: 'Get the current weather for a location', inputSchema: z.object({ location: z.string() }), execute: async ({ location }) => ({ location, temperatureC: 18 }), }), }, });
console.log(result.text);}
main().catch(console.error);Copy link to headingMore models by Sakana AI
| Model |
|---|
| 256K | 0.8 s | 217 tps | $0.95/M | $4/M | Read$0.15/M | — | +3 | | 08/03/2026 |
Copy link to headingAbout Fugu Ultra
Fugu Ultra was released June 21, 2026 as Sakana AI's premium tier in the Fugu line. Instead of answering with a single network, Fugu Ultra runs a multi-agent system behind one model API. A lightweight coordinator assigns Thinker, Worker, and Verifier roles across a pool of frontier models, then routes between one and three agents depending on the problem. The approach builds on Sakana AI's published TRINITY and Conductor research.
Sakana AI tuned Fugu Ultra for maximum answer quality rather than low latency, drawing on a deeper, fixed agent pool and spending more compute per request. Early users applied Fugu Ultra to AI research, paper reproduction, cybersecurity analysis, and literature and patent investigations. In Sakana AI's published evaluations, Fugu Ultra scores 73.7 on SWE-Bench Pro, 95.5 on GPQA-Diamond, and 50.0 on Humanity's Last Exam.
Fugu Ultra supports a context window of 1M tokens with output up to 1M tokens, plus prompt caching for repeated context. Through AI Gateway, you call Fugu Ultra with a unified API key, automatic retries, and built-in observability, using the AI SDK, Chat Completions API, Responses API, Messages API, or other API formats.
Copy link to headingWhat To Consider When Choosing a Provider
- Configuration: Fugu Ultra optimizes for answer quality, not speed. Each request can fan out across multiple coordinated agents, so responses take longer than single-model calls. See live metrics on this page, and reserve Fugu Ultra for problems where quality justifies the wait.
- Configuration: Pricing is tiered by context length. Requests beyond 272K tokens bill at higher rates for input, output, and cached input. Track actual spend with AI Gateway's built-in observability, and trim prompts where you can.
- Configuration: The agent pool behind Fugu Ultra is fixed, and per-request routing details aren't exposed. Teams with strict model-provenance requirements should confirm the orchestrated approach fits their compliance needs before deploying. Fugu Ultra is available through Sakana AI.
- Zero Data Retention: Zero Data Retention is offered on a per-provider and model basis. See the documentation for details.
- Authentication: AI Gateway authenticates requests using an API key or OIDC token. You do not need to manage provider credentials directly.
Copy link to headingWhen to Use Fugu Ultra
Best for
- Deep Research Workflows: Literature reviews, patent investigations, and paper reproduction benefit from coordinated multi-agent analysis
- Hard Multi-Step Problems: Engineering and scientific questions where answer quality outweighs latency and cost per request
- Cybersecurity Analysis: Careful multi-step reasoning over code, configurations, and threat reports fits the verifier-backed workflow
- Long-Context Investigations: The context window of 1M tokens fits large codebases, document sets, and extended research threads
- Quality-Critical Agent Steps: Route your hardest pipeline steps to Fugu Ultra while cheaper models handle routine work
Consider alternatives when
- Latency-Sensitive Applications: Multi-agent coordination adds response time, so single-model options such as GPT-5.4 or Gemini 3.5 Flash fit interactive chat better
- High-Volume Simple Tasks: Classification, extraction, and summarization run cheaper on efficiency models such as DeepSeek V4 Flash or Kimi K2.6
- Predictable Single-Model Behavior: Teams that must know exactly which model produced each answer should pick a conventional model, since Fugu Ultra routes internally
- Budget-Constrained Workloads: Premium per-token rates make Fugu Ultra expensive for routine generation at high volume
Copy link to headingConclusion
Fugu Ultra packages Sakana AI's multi-agent orchestration research into a single endpoint tuned for maximum answer quality on hard problems. For research, security analysis, and quality-critical agent steps, Fugu Ultra is available through AI Gateway with unified billing, observability, and provider routing.
Copy link to headingFrequently Asked Questions
How is Fugu Ultra different from a conventional language model?
Fugu Ultra is a multi-agent system delivered as a single model API. A lightweight coordinator assigns Thinker, Worker, and Verifier roles across a pool of frontier models, routing between one and three agents per problem. You call one endpoint and receive one answer, but multiple coordinated models may work on the request.
What is the context window for Fugu Ultra?
1M tokens, with output up to 1M tokens. That fits large codebases, long document sets, and extended research threads in a single request. Requests beyond 272K tokens bill at higher tiered rates.
How much does Fugu Ultra cost through AI Gateway?
Current rates appear in the pricing panel on this page and update as providers adjust them. Pricing is tiered by context length, with higher rates for input, output, and cached input beyond 272K tokens.
Does Fugu Ultra support Zero Data Retention?
Zero Data Retention is not currently available for this model. Zero Data Retention is offered on a per-provider basis. See https://vercel.com/docs/ai-gateway/capabilities/zdr for details.
How do I authenticate with Fugu Ultra through AI Gateway?
AI Gateway provides a unified API key. You don't need a separate Sakana AI account. Configure your API key, then use the model identifier to route requests through the AI SDK, Chat Completions API, Responses API, or Messages API. BYOK is also supported if you have a direct provider account.
Why do responses from Fugu Ultra take longer than single-model calls?
Each request can involve multiple coordinated agents working in sequence, including verification passes. That extra orchestration improves answer quality on hard problems but adds latency. See live metrics on this page, and use faster single-model options for interactive workloads.
Which underlying models does Fugu Ultra use to answer a request?
Sakana AI draws from a fixed pool of frontier models for Fugu Ultra and doesn't disclose per-request routing. If your compliance requirements demand knowing exactly which model handled each request, choose a conventional single model instead.
Your use is subject to Sakana AI's Terms & Privacy Policies.