Sakana AI: Fugu
Fugu is a reasoning model from Sakana AI released on Jun 15, 2026. It reads text and images and writes text, with a 1M token context window and up to 1M tokens per reply.
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It supports tool calling and structured JSON output.
- Modalities
- In / out price
- n/a
- Context
- 1M
- Max output
- 1M
- Released
- Jun 15, 2026
- Knowledge cutoff
- n/a
- Tool calling
- Structured output
- Reasoning
- Prompt caching
- Open weights
- Free to use
Supported request parameters
What you can set when you call Fugu through an OpenAI compatible API.
- Tools
tools - Structured outputs
structured_outputs - Reasoning
reasoning
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Fugu questions
What is the context window of Fugu?
1,000,000 tokens of input, and it can write up to 1,000,000 tokens in one reply. As a rough guide, a million tokens is around 750,000 English words.
Does Fugu support tool calling?
Yes. It accepts tool definitions and can return JSON that matches a schema, which is what an agent needs to call your APIs.
Is Fugu open source?
No. Sakana AI serves it through an API only, so you cannot download the weights or host it yourself.
When was Fugu released?
Jun 15, 2026.
Catalog data from models.dev (MIT licensed), refreshed daily, last on Oct 15, 2026. The summary is written from these facts.