LLMsakana

Sakana: Fugu Ultra v2

Fugu Ultra v2 is the higher-performance model in Sakana AI's Fugu family. Rather than a single monolithic model, Fugu is a learned multi-agent orchestration system: a language model trained to...

Anyone in the Project can @-mention Sakana: Fugu Ultra v2 with the team's shared context - pooled credits, one chat, one memory.

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Starter is free forever - 1 Project, 100 credits/month, 1 MCP. No card.

Verdict

Fugu Ultra v2 offers a massive 1M token context window at mid-tier pricing, making it a strong choice for document-heavy workflows where you need to process entire codebases or lengthy research papers in one pass. The $5/$30 per Mtok pricing sits between budget and premium tiers, though output costs add up quickly on generation-heavy tasks. Without public benchmarks, you're trading proven performance metrics for Sakana's context capacity advantage. Reach for this when context length matters more than established leaderboard rankings.

Best for

  • Processing entire codebases in context
  • Multi-document research synthesis
  • Long-form content analysis and summarization
  • Technical documentation review at scale
  • Contract analysis across multiple files

Strengths

The 1M token context window handles what most models cannot: entire repositories, multi-file legal documents, or dozens of research papers in a single conversation. Multimodal support adds flexibility for screenshot analysis and document images alongside text. The $5 input pricing makes it economical to load massive contexts compared to premium alternatives. Sakana's focus on context efficiency suggests the model maintains coherence across the full window better than models that technically support long contexts but degrade in practice.

Trade-offs

The absence of public benchmarks means you cannot compare reasoning quality, coding ability, or instruction-following against established models like GPT-4o or Claude Sonnet. The $30 output pricing becomes expensive on generation-heavy tasks—summarizing that 1M token context into a 10K token report costs $300 in output tokens alone. Early-stage model from a less-established provider carries higher risk of unexpected behavior or capability gaps compared to OpenAI, Anthropic, or Google offerings.

Specifications

Provider
sakana
Category
llm
Context length
1,000,000 tokens
Max output
128,000 tokens
Modalities
text, image, file
License
proprietary
Released
2026-09-11

Pricing

Input
$5.00/Mtok
Output
$30.00/Mtok
Model ID
sakana/fugu-ultra-v2

Per-token prices show what the model costs upstream. On Switchy your team draws from one shared org credit pool - one plan, one balance for everyone.

Team cost calculator

Estimated monthly spend
$220.00
17.6M tokens / month
5 seats · 80 msgs/day

Switchy meters this against your org's shared credit pool - one plan, one balance for everyone.

Providers

ProviderContextInputOutputP50 latencyThroughput30d uptime
sakana1000k$5.00/Mtok$30.00/Mtok———

Performance

Performance snapshots are collected daily. Check back after the next ingestion run.

Benchmarks

Public benchmark scores are not available yet for this model. Check back after the next ingestion run.

Works well with

Top MCPs

Compatibility data comes from first-party telemetry; once we have enough co-usage signal, top MCPs for this model will appear here.

How Switchy teams use it

Not enough Projects have used this model yet to share anonymised team stats. We wait for at least 50 distinct Projects per week before publishing any aggregate.

Starter prompts

Codebase Architecture Review

Review this complete codebase and identify: 1) the core architectural patterns used, 2) three areas of technical debt with specific file references, 3) dependencies between major modules. Focus on structural issues that span multiple files.

Multi-Paper Literature Synthesis

I've provided 15 research papers on the same topic. Identify: 1) the three most consistent findings across papers, 2) two areas where papers contradict each other with specific citations, 3) gaps that none of these papers address.

Contract Cross-Reference Analysis

Compare these five contracts and flag: 1) any conflicting terms or obligations, 2) clauses present in some but missing in others, 3) the most restrictive version of each key term. Reference specific section numbers.

Technical Documentation Audit

Audit this full documentation set for: 1) sections that contradict each other, 2) features mentioned in code comments but missing from docs, 3) three areas where examples would clarify confusing explanations.

Long-Form Content Restructure

This document has grown organically and needs restructuring. Identify: 1) concepts explained multiple times in different sections, 2) a more logical ordering of the main sections, 3) three places where splitting or merging sections would improve clarity.

Example outputs

Illustrative - representative of the model's voice and quality, not literal recordings.

Prompt

Review this 847-page technical specification document for our new API and identify any inconsistencies in authentication flow descriptions across sections 3, 7, and 12.

Output

The model would produce a detailed cross-reference analysis highlighting three key inconsistencies: Section 3.4 describes OAuth2 token refresh using a 15-minute window, while Section 7.2 specifies 30 minutes for the same operation. Section 12.1 introduces a third-party JWT validation step absent from the initial flow diagram in Section 3. Additionally, the error code taxonomy differs—Section 3 uses AUTH_001 through AUTH_015, but Section 12 references AUTH_100 series codes without defining them. The analysis would include page numbers, exact quote excerpts, and a reconciliation table showing which specification should be considered authoritative based on document versioning metadata.

Notes

This showcases the 1M token context window handling an entire technical document at once—a task that would require chunking and reassembly in smaller-context models. The $5/$30 pricing means this single query costs roughly $4.24 for input alone, making it expensive for casual use but viable for high-stakes document review where accuracy justifies cost.

Prompt

Generate a Python script that processes these 15 CSV files (attached), normalizes column names across inconsistent schemas, and outputs a unified dataset with data quality metrics.

Output

The model would produce a complete Python script using pandas, incorporating schema detection logic that maps variations like 'customer_id', 'CustomerID', and 'cust_id' to a single canonical field. The script would include error handling for encoding issues, generate a summary report showing row counts, null percentages, and data type mismatches per file, and write both the cleaned dataset and a JSON quality report. The code would be production-ready with logging, type hints, and a command-line interface for specifying output paths.

Notes

File upload support lets the model inspect actual data structure rather than working from descriptions, reducing back-and-forth clarification. The multimodal capability here means it can handle CSVs alongside images of data dictionaries or schema diagrams in the same prompt. However, at $30/Mtok output, a 500-line script costs about $0.015—negligible per query but accumulates quickly in iterative development workflows.

Prompt

Explain the architectural decisions in this codebase (12 TypeScript files attached) and suggest three refactoring opportunities that would improve testability without breaking existing API contracts.

Output

The model would provide a structured analysis beginning with an architecture overview: the codebase uses a layered service pattern with tight coupling between the data access layer and business logic, making unit testing difficult. It would identify three concrete refactoring opportunities: (1) extracting database queries into a repository pattern with interface definitions, enabling mock injection; (2) replacing direct environment variable access with a configuration object passed through constructors; (3) splitting the 450-line UserService class into domain-specific services while maintaining the existing public methods as a facade. Each suggestion would include before/after code snippets and migration steps that preserve backward compatibility.

Notes

This demonstrates the model's ability to reason across multiple files simultaneously and maintain awareness of API surface area—critical for real-world refactoring where breaking changes have downstream costs. The image modality support means developers could also include architecture diagrams or whiteboard photos for additional context, though text-only analysis remains the primary strength here.

Use-case deep-dives

Multi-document contract analysis

When 1M tokens lets legal teams batch-review entire deal folders

A 4-person legal ops team at a Series B SaaS company needs to extract termination clauses from 80 vendor contracts before renewal season. Fugu Ultra v2's 1M-token window means they can load 15-20 full contracts in a single prompt and ask for a structured comparison table—no chunking, no context loss across documents. At $5/Mtok input, a 600k-token batch costs $3 to process, and the $30/Mtok output rate stays reasonable because the model returns concise tables, not full rewrites. The trade-off: without public benchmarks, you're flying blind on accuracy for nuanced legal reasoning. If your contracts have standard boilerplate and you can spot-check the first few outputs, this is a fast, cheap way to triage. If you're dealing with bespoke IP clauses or need courtroom-grade precision, wait for benchmark data or use a model with proven legal evals.

Customer support ticket triage

Why Fugu Ultra v2 struggles against faster, cheaper chat models here

A 12-person e-commerce support team fields 300 tickets/day and wants to auto-tag urgency and route to the right specialist. Fugu Ultra v2's $30/Mtok output pricing makes it expensive for high-volume classification: even short 200-token responses add up to $6/1k tickets. The 1M-token context is overkill—most tickets are under 500 tokens, and you don't need to reference a year of chat history to decide if someone's order is lost or delayed. Models like GPT-4o-mini or Claude Haiku run $0.60-$1.50/Mtok output and handle simple triage at 80%+ accuracy. Fugu Ultra v2 makes sense only if you're doing complex, multi-turn escalations where you need to pull in dozens of past tickets and knowledge-base articles in one context. For straightforward tagging at scale, you're paying 20x more than you need to.

Codebase-wide refactoring planning

When million-token context turns a 3-day audit into a 20-minute prompt

A 5-engineer startup wants to migrate a 40k-line Python monolith from Flask to FastAPI and needs a file-by-file change plan. Fugu Ultra v2's 1M-token window lets them upload the entire codebase—models, routes, tests, config—and ask for a dependency graph plus a sequenced refactor roadmap. At $5/Mtok input, the ~200k-token codebase costs $1 to ingest, and the detailed output plan runs another $3-5. The alternative is manually tracing imports for days or chunking the code across 20 prompts and stitching answers together. The risk: no public benchmarks means you can't verify if the model correctly parses complex decorators or async patterns. Run the first plan on a isolated module, validate the suggestions in CI, then scale up. If the model hallucinates imports or misses edge cases, fall back to a code-specialized model with proven HumanEval scores.

Frequently asked

Is Fugu Ultra v2 good for long-document analysis?

Yes. The 1M token context window handles entire codebases, legal contracts, or research papers in a single prompt. That's roughly 750,000 words — enough for most real-world documents without chunking. The multimodal support also lets you mix text with images or PDFs in the same context.

Is Fugu Ultra v2 cheaper than GPT-4o for high-volume tasks?

No. At $5 input and $30 output per Mtok, Fugu costs 2.5× more than GPT-4o ($2 input, $10 output). For tasks generating long outputs — summaries, reports, code — that $30 output rate adds up fast. Consider GPT-4o or Claude Sonnet 3.5 if cost matters more than the 1M window.

Can Fugu Ultra v2 process multiple file types in one prompt?

Yes. It accepts text, images, and file uploads together. You can feed it a PDF, a screenshot, and a CSV in the same request. Useful for workflows like 'analyse this contract (PDF), compare it to this spreadsheet, and explain the chart in this image'.

How does Fugu Ultra v2 compare to the original Fugu model?

No public benchmarks exist for either version, so performance differences are unclear. The v2 label suggests improvements, but without MMLU, HumanEval, or latency data, you're relying on vendor claims. Test it yourself on your use case before committing to production.

Should I use Fugu Ultra v2 for real-time chat applications?

Probably not. The high output cost ($30/Mtok) makes conversational use expensive, and we have no latency benchmarks. For chat, GPT-4o or Claude Sonnet 3.5 offer better-documented speed and lower per-token costs. Use Fugu for batch jobs where the 1M window justifies the price.

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Data last verified 13 hours ago.Sources aggregated hourly to weekly. See docs/architecture/model-directory.md.