Claude Fable 5 vs Fusion
The newest Anthropic model — first Mythos-class made generally available. vs Multi-model panel — Fable 5 + GPT-5.5, ensembled. Beats Fable 5 at half the price.
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 Claude Fable 5 and Fusion, 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.
Claude Fable 5 · Selected from Agent OS for the highest-stakes one-shot work — replacing Opus 4.8 as the safety net on hard prompts. Bench scoring pending.
Fusion · Dispatched from Agent OS for research-heavy prompts where ensemble accuracy outweighs single-model speed.
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
Claude Fable 5
Strengths
- Anthropic's most capable publicly-available model — vendor claim: 'capabilities exceed those of any model we've ever made generally available'
- Tops external SWE-bench Verified at 95.0% in Julian's three-dragons writeup
- Top-tier plan quality (9.1/10) on Kilo's plan-vs-build rubric
Trade-offs
- No goldiebench per-task scores yet — bench rank pending a published head-to-head guide
- Premium pricing; Fusion premium panel reportedly out-scores it at half the API cost
Fusion
Strengths
- Premium Fusion panel scored 69.0% on DRACO deep-research benchmark — beats solo Fable 5 by +3.7 points
- Budget panel ties Fable 5 at ~64.7% for roughly half the cost
- Vendor-agnostic — model panel can swap as new frontier releases land
Trade-offs
- Ensemble latency higher than any single model (panel calls run in parallel but the slowest still gates the response)
- No per-task goldiebench scoring yet — bench rank pending
Pricing & context — the spec sheet
| Spec | Claude Fable 5 | Fusion |
|---|---|---|
| Vendor | Anthropic | OpenRouter |
| Context window | 200,000 tokens (1M with extended thinking) | Varies — depends on which panel models are dispatched |
| Price | Anthropic API pricing | OpenRouter Fusion API pricing |
| Pricing detail | Released alongside Mythos 5 on June 9, 2026 as the publicly-available member of the new Mythos class. Premium per-token pricing on the Anthropic API; available everywhere Opus 4.8 ships. | OpenRouter's Fusion API dispatches a single prompt to multiple frontier models and ensembles the answers. Premium panel: Fable 5 + GPT-5.5. Budget panel: cheaper open-weights models. Roughly half the per-token cost of a Fable 5 solo call. |
| Release | 2026-06-09 | 2026-06-14 |
| 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 Claude Fable 5 and Fusion both into the Agent Operating System and dispatch each from the kanban by task type — mission-critical one-shot builds where you want anthropic's newest reasoning → Claude Fable 5, deep-research workflows where panel consensus beats single-model answers → Fusion. That's the same setup I run for the 3,600+ founders inside the AI Profit Boardroom.
FAQ — Claude Fable 5 vs Fusion
Which is better, Claude Fable 5 or Fusion?
On Goldie Bench, Claude Fable 5 averages no scored verdicts yet across the shared tasks, with 0 gold, 0 silver, 0 bronze overall. Fusion 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 Claude Fable 5 cost vs Fusion?
Claude Fable 5: Released alongside Mythos 5 on June 9, 2026 as the publicly-available member of the new Mythos class. Premium per-token pricing on the Anthropic API; available everywhere Opus 4.8 ships. Fusion: OpenRouter's Fusion API dispatches a single prompt to multiple frontier models and ensembles the answers. Premium panel: Fable 5 + GPT-5.5. Budget panel: cheaper open-weights models. Roughly half the per-token cost of a Fable 5 solo call.
What's the context window for Claude Fable 5 vs Fusion?
Claude Fable 5 has a 200,000 tokens (1M with extended thinking) context window. Fusion has a Varies — depends on which panel models are dispatched context window.
When should I pick Claude Fable 5 over Fusion?
Pick Claude Fable 5 for: Mission-critical one-shot builds where you want Anthropic's newest reasoning; Long-context work using extended thinking up to 1M tokens; Plan-heavy multi-step tasks where intelligence in the plan matters more than the build. The trade-off is the weaknesses we logged on the bench: No goldiebench per-task scores yet — bench rank pending a published head-to-head guide; Premium pricing; Fusion premium panel reportedly out-scores it at half the API cost.
When should I pick Fusion over Claude Fable 5?
Pick Fusion for: Deep-research workflows where panel consensus beats single-model answers; Cost-sensitive operators who want Fable-5-class output at ~half the bill; Production agents that benefit from vendor-redundancy on every call. The trade-off is the weaknesses we logged on the bench: Ensemble latency higher than any single model (panel calls run in parallel but the slowest still gates the response); No per-task goldiebench scoring yet — bench rank pending.
How does Goldie Bench score Claude Fable 5 vs Fusion?
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:
Claude Fable 5 vs Opus 4.8 Fusion vs Opus 4.8 Claude Fable 5 vs GLM-5.2 Fusion vs GLM-5.2 Claude Fable 5 vs Grok Fusion vs Grok Claude Fable 5 vs Qwen 3.7 Fusion vs Qwen 3.7Full model pages: Claude Fable 5 · Fusion · 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 3,600+ founders shipping with it every day all live inside the AI Profit Boardroom.