Fugu Ultra 1.1 vs Claude Mythos 5
Sakana's multi-agent orchestrator, v1.1 — routes experts per request. vs Restricted-access flagship — vetted partners only.
What I tested — same prompt, two models
I run the same fixed prompt set through every new model the day it drops — same string, one shot, single HTML file out — and I score the result 0–10 on whether it ran, how close it hit the brief, and how good it looked. Below is what came out when I gave the exact same prompts to Fugu Ultra 1.1 and Claude Mythos 5, side by side, on 0 shared tasks inside the Agent Operating System.
Both models were given identical prompts inside the Agent Operating System — no help, no iteration, no "best of N" tricks. I run each prompt once, save the HTML file the model produces, and score it 0–10 on whether it ran, how close it hit the brief, and how good it looked. The scoring is mine. The verdicts below are pulled from my source comparison guides at agentos.guide where I publish every score and the reasoning behind it.
Fugu Ultra 1.1 · Benched on GoldieBench via Sakana's Responses API (fugu-ultra-v1.1, xhigh reasoning). Game tasks use the skill-infused threejs-game-director prompt plus a controls+graphics fix loop with an anti-regression clamp, judged on a real mid-play frame by the same Opus judge as the field.
Claude Mythos 5 · Not currently dispatched from Agent OS — no public API. Tracked for news coverage only.
Side-by-side on 0 shared tasks
Click any cell to play that model's actual one-shot attempt. Medals are derived from my 0–10 scores per task (highest = 🥇, second = 🥈, third = 🥉).
Strengths & weaknesses I logged
Fugu Ultra 1.1
Strengths
- Orchestrates 1-3 expert agents per request and synthesises their answers
- Reported SWE-Bench Pro 73.7 — above Opus 4.8 and GPT-5.5 on Sakana's table
- OpenAI- and Anthropic-compatible API — drop-in for Codex and Claude Code
Trade-offs
- Benched as a partial run until the full 50-task batch completes
- Region-locked: unavailable across the EU/EEA/UK/CH — access depends on where you are
Claude Mythos 5
Strengths
- Highest-class Anthropic model — sits above Fable 5 in the Mythos line
- Same Mythos-class capability profile as Fable 5 (with restrictions)
Trade-offs
- No public API access — can't be benched against the open field
- Restricted distribution makes it effectively unavailable to most builders
Pricing & context — the spec sheet
| Spec | Fugu Ultra 1.1 | Claude Mythos 5 |
|---|---|---|
| Vendor | Sakana AI | Anthropic |
| Context window | 1,000,000-token context window | 200,000 tokens |
| Price | API · orchestration billed | Restricted access — vetted partners only |
| Pricing detail | Sakana's Fugu Ultra v1.1 — a multi-agent system served as a model: an orchestrator routes each request across one to three expert agents and synthesises the answer. Reported (v1.0): SWE-Bench Pro 73.7, LiveCodeBench 93.2, GPQA Diamond 95.5. NOTE: Sakana geo-blocks the EU/EEA/UK/Switzerland pending GDPR compliance — benched from an allowed region. | Mythos 5 is the un-released sibling of Fable 5. Same Mythos class, restricted to vetted partners. Made headlines mid-June 2026 when reports of a White-House-driven ban over China access dominated AI press. |
| Release | 2026-07 | 2026-06-09 |
| Bench coverage | 0/0 scored · avg — | 0/0 scored · avg — |
The verdict — which should you pick?
Not enough scored shared tasks yet for a head-to-head average. The live demos for both are on the matrix above — play them and form your own opinion.
If you only run one of these inside your stack, the head-to-head average above is the call. If you can run both, my honest play is to wire Fugu Ultra 1.1 and Claude Mythos 5 both into the Agent Operating System and dispatch each from the kanban by task type — hard, high-stakes coding and reasoning where answer quality beats latency → Fugu Ultra 1.1, vetted enterprise partners with mythos-class access → Claude Mythos 5. That's the same setup I run for the 4,000+ founders inside the AI Profit Boardroom.
FAQ — Fugu Ultra 1.1 vs Claude Mythos 5
Which is better, Fugu Ultra 1.1 or Claude Mythos 5?
On Goldie Bench, Fugu Ultra 1.1 averages no scored verdicts yet across the shared tasks, with 0 gold, 0 silver, 0 bronze overall. Claude Mythos 5 averages no scored verdicts yet, with 0 gold, 0 silver, 0 bronze. Not enough scored shared tasks yet to call a winner.
How much does Fugu Ultra 1.1 cost vs Claude Mythos 5?
Fugu Ultra 1.1: Sakana's Fugu Ultra v1.1 — a multi-agent system served as a model: an orchestrator routes each request across one to three expert agents and synthesises the answer. Reported (v1.0): SWE-Bench Pro 73.7, LiveCodeBench 93.2, GPQA Diamond 95.5. NOTE: Sakana geo-blocks the EU/EEA/UK/Switzerland pending GDPR compliance — benched from an allowed region. Claude Mythos 5: Mythos 5 is the un-released sibling of Fable 5. Same Mythos class, restricted to vetted partners. Made headlines mid-June 2026 when reports of a White-House-driven ban over China access dominated AI press.
What's the context window for Fugu Ultra 1.1 vs Claude Mythos 5?
Fugu Ultra 1.1 has a 1,000,000-token context window context window. Claude Mythos 5 has a 200,000 tokens context window.
When should I pick Fugu Ultra 1.1 over Claude Mythos 5?
Pick Fugu Ultra 1.1 for: Hard, high-stakes coding and reasoning where answer quality beats latency; Agentic workflows in Codex / Claude Code via the drop-in provider config; One-shot builds you want a panel of experts on, not a single model. The trade-off is the weaknesses we logged on the bench: Benched as a partial run until the full 50-task batch completes; Region-locked: unavailable across the EU/EEA/UK/CH — access depends on where you are.
When should I pick Claude Mythos 5 over Fugu Ultra 1.1?
Pick Claude Mythos 5 for: Vetted enterprise partners with Mythos-class access; (For everyone else: read the Mythos ban coverage instead of waiting for access). The trade-off is the weaknesses we logged on the bench: No public API access — can't be benched against the open field; Restricted distribution makes it effectively unavailable to most builders.
How does Goldie Bench score Fugu Ultra 1.1 vs Claude Mythos 5?
Every demo on this page was built by Julian Goldie inside the Agent Operating System — same fixed prompt for both models, one shot, single HTML file out. Each result gets a 0–10 score on whether it ran, how close it hit the brief, and how good it looked. The highest score on each task gets gold; second gets silver; third gets bronze. See methodology for full provenance.
Related comparisons
Other head-to-heads using the same scoring system:
Fugu Ultra 1.1 vs Fusion Claude Mythos 5 vs Fusion Fugu Ultra 1.1 vs Hermes MoA Claude Mythos 5 vs Hermes MoA Fugu Ultra 1.1 vs GPT-5.6 Sol Claude Mythos 5 vs GPT-5.6 Sol Fugu Ultra 1.1 vs Claude Fable 5 Claude Mythos 5 vs Claude Fable 5Full model pages: Fugu Ultra 1.1 · Claude Mythos 5 · back to the leaderboard
Run this stack yourself.
Every demo on this bench was built inside the Agent Operating System — one prompt, one shot, single HTML file out. The Agent OS, the prompts, the templates, the weekly walkthroughs and 4,000+ founders shipping with it every day all live inside the AI Profit Boardroom.