Fugu Ultra vs Grok 4.5

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 and Grok 4.5, side by side, on 41 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 · Dispatched from Agent OS as the panel-ensemble alternative to OpenRouter Fusion. Bench scored by Claude judge against the same 42 prompts as every other model.

Grok 4.5 · Benched one-shot on the same GoldieBench game prompts as the field, with the threejs-game-director patterns baked into each prompt; weak builds iterated by Grok 4.5 itself (the model authors every fix, never hand-patched). Wired into the Agent OS as the newest engine.

Where Fugu Ultra beat Grok 4.5

The tasks where I gave Fugu Ultra a higher 0–10 score on the same prompt — with the actual commentary from my source guides.

Where Grok 4.5 beat Fugu Ultra

The tasks where I gave Grok 4.5 a higher 0–10 score on the same prompt — with the actual commentary from my source guides.

Strengths & weaknesses I logged

Pricing & context — the spec sheet

The verdict — which should you pick?

Across 41 scored shared tasks, the averages are essentially tied — Fugu Ultra 7.96 vs Grok 4.5 7.68. This isn't the comparison where one wins; it's the comparison where you pick based on context, pricing, and what you're actually trying to ship.

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 and Grok 4.5 both into the Agent Operating System and dispatch each from the kanban by task type — teams that want fusion-class quality but need a different vendor risk profile → Fugu Ultra, one-shot end-to-end app + game builds from a single prompt → Grok 4.5. That's the same setup I run for the 4,000+ founders inside the AI Profit Boardroom.

FAQ — Fugu Ultra vs Grok 4.5

Which is better, Fugu Ultra or Grok 4.5?

On Goldie Bench, Fugu Ultra averages 7.96/10 across the shared tasks, with 6 gold, 6 silver, 5 bronze overall. Grok 4.5 averages 7.68/10, with 12 gold, 34 silver, 2 bronze. Fugu Ultra wins the head-to-head 28–13.

How much does Fugu Ultra cost vs Grok 4.5?

Fugu Ultra: Sakana's multi-agent orchestration: a single API call internally dispatches to multiple frontier models and synthesises the answer. Subscription plans run $20-$200/mo (Standard / Pro / Max); PAYG is $5/M input + $30/M output for Fugu Ultra. Direct competitor to OpenRouter Fusion's panel approach. Grok 4.5: ~4.2x fewer output tokens than Opus 4.8 on SWE-Bench Pro (15,954 vs 67,020 avg) and served at ~80 TPS, so real cost/latency is well below the sticker. Free for a limited time in Grok Build + Cursor.

What's the context window for Fugu Ultra vs Grok 4.5?

Fugu Ultra has a 272,000 tokens with the standard rate. Calls exceeding 272K context are billed at the higher 'long-context' rates. context window. Grok 4.5 has a xAI's smartest model, built for coding + agentic tasks; trained alongside Cursor. Default model in Grok Build. Benched here via OpenRouter (x-ai/grok-4.5). context window.

When should I pick Fugu Ultra over Grok 4.5?

Pick Fugu Ultra for: Teams that want Fusion-class quality but need a different vendor risk profile; Operators avoiding export-controlled providers (Sakana emphasises this in their pitch); Deep-research workflows where ensemble verdicts beat single-model answers. The trade-off is the weaknesses we logged on the bench: Panel orchestration adds latency — even a 'pong' burns ~2k orchestration tokens; Newer than Fusion; less community calibration on long-tail prompts.

When should I pick Grok 4.5 over Fugu Ultra?

Pick Grok 4.5 for: One-shot end-to-end app + game builds from a single prompt; Cost/latency-sensitive agentic coding loops (token-efficient + fast); Office-work automation (Excel/PowerPoint/Word via Grok Build). The trade-off is the weaknesses we logged on the bench: Raycaster/FPS (doom) under-renders + walks out of bounds one-shot; needed multiple self-fix passes; Occasional TDZ/init bug blanks a build to black (racing) — recovered by the model itself in one pass; Not available in the EU until mid-July 2026.

How does Goldie Bench score Fugu Ultra vs Grok 4.5?

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:

Full model pages: Fugu Ultra · Grok 4.5 · back to the leaderboard