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Sakana AI

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.

Vision (Image)Tool UseReasoning
index.ts
import { streamText } from 'ai'


const result = streamText({
  model: 'sakana/fugu-ultra',
  prompt: 'Why is the sky blue?'
})
OverviewAboutProvidersLatencyUptimeStatusFAQ

Frequently 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.