Claude Opus 5.5 (max) vs Muse Spark 1.3 (thinking)
Should you write with Claude Opus 5.5 (max) or Muse Spark 1.3 (thinking)? On this page the only thing that changes is the model. Both wrote their own version of the scripts behind 10 of my What's AI videos, five drafts per script, and four judges (three LLM judges from three model families plus Jev, a typed judge from TypeSafe) scored every draft blind, with my finished script as the reference. Claude Opus 5.5 (max) leads overall, 90.8 to 82.5.
The verdict
No contest on quality. Claude Opus 5.5 (max effort) is #1 and Muse Spark 1.3 (thinking) is #83, over a thousand Elo apart, and Muse doesn't win a single metric. The biggest gap is Length Adherence, about thirty-four points: Muse misses the target length often enough that you'd be cutting or padding most scripts. What Muse has is price and speed, about four cents a script against about $2.75, and just over a minute instead of seventeen. That's a case for throwaway first drafts, not for a script you want to record.
Pick Claude Opus 5.5 (max effort) when you want a script you can record with minimal changes.
Pick Muse Spark 1.3 (thinking) for quick, cheap first drafts you plan to rewrite.
How to read these numbers
Overall vs Elo. Overall is the weighted rubric score. Elo compares each model's five-draft average with every other model's, script by script, and counts gaps inside run-to-run noise as draws, so it rewards winning often and can disagree with overall.
Reading the Elo intervals. Each 95% range comes from resampling every model's recorded run scores on each task and re-ranking. Comparing these separate ranges does not test the Elo gap between two models: far apart is strong evidence, and overlap isn't a tie. The tasks stay fixed, so the ranges say nothing about new tasks (the long version).
Metric by metric: where the gap comes from
Blue is Claude Opus 5.5 (max), orange is Muse Spark 1.3 (thinking), and the solid bar takes the metric. The weight under each name is how much it counts toward the overall. Weighted by how much each metric counts, Length Adherence does the most to put Claude Opus 5.5 (max) ahead: it leads there by 33.7 points. If you care about one thing, say voice or length, go straight to that row.
Cost, speed, and consistency
Quality is half the decision. The other half is what each script costs you, how long you wait, and how often you get a bad draft. The lead has a price: Claude Opus 5.5 (max) costs about 67x as much per script as Muse Spark 1.3 (thinking).
| Claude Opus 5.5 (max) | Muse Spark 1.3 (thinking) | |
|---|---|---|
| Overall / 100 | 90.8 | 82.5 |
| Writing Elo | 2683 | 1629 |
| Score spread across drafts (± overall std) | 1.290 | 2.600 |
| Cost per script (USD) | 2.746 | 0.041 |
| Avg time per script (min) | 17.1 | 1.3 |
| Open weights | No | No |
Green wins the row, and for spread, cost and time, lower wins. Cost is one script at recorded list prices, uncached and without judging, so your real bill will differ. Spread is how much the overall score moves across a model's drafts, and time is the average time to get one accepted script, retries included.
Want the script-by-script detail? Full scorecards: Claude Opus 5.5 (max) · Muse Spark 1.3 (thinking). The whole scoring pipeline is on the methodology page.
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