Claude Opus 5.5 vs Muse Spark 1.3

At a glance

• Capability index

  • Claude Opus 5.5167.3
  • Muse Spark 1.3156.8

  Claude Opus 5.5 is 10.6 points higher.

• Price per 1M tokens

  • Claude Opus 5.5$8.00
  • Muse Spark 1.3$2.00

  Muse Spark 1.3 is 4 times cheaper.

• Context window

  • Claude Opus 5.51M tokens
  • Muse Spark 1.31M tokens

  They take in about the same.

• Released

  • Claude Opus 5.5Sep 22, 2026
  • Muse Spark 1.3Sep 2, 2026

  Claude Opus 5.5 is 20 days newer.

Where each scores higher

On the 19 tests both have taken, each on its own scale. A gap of a point or two can sit within a test’s margin of error.

Level on Arena coding.

3 more tests have results for only one of them; the table below lists every result.

Everything side by side

Comparison of Claude Opus 5.5 vs Muse Spark 1.3

Measure	Claude Opus 5.5Anthropic	Muse Spark 1.3Meta AI
Model
Maker	Anthropic	Meta AI
Sold here by	Anthropic	DevPass (LLM Gateway)
API model ID	claude-opus-5-5	muse-spark-1.3
Released	Sep 22, 2026	Sep 2, 2026
Knowledge cutoff	Jun 2026	Not reported
Weights	Closed: hosted access only	Closed: hosted access only
Developer’s country	United States	United States
Hosts selling it	35including Anthropic directly	11
Test results
Capability index	167.3 (best of these models)#1 of 274	156.8#19 of 274
LiveBench overall	83.2% (best of these models)#2 of 66	81.6%#7 of 66
Arena text	1504 (best of these models)#4 of 413	1494#9 of 413
LiveBench coding	89.3% (best of these models)#2 of 66	81.1%#17 of 66
Arena WebDev	1815 (best of these models)#1 of 138	1657#14 of 138
Arena coding	1539#12 of 408	1539#11 of 408
LiveBench mathematics	97.1% (best of these models)#1 of 66	96.0%#12 of 66
Mock AIME 2024–2025	100.0% (best of these models)#1 of 297	99.2%#15 of 297
FrontierMath Tiers 1–3	91.2% (best of these models)#3 of 114	74.4%#19 of 114
FrontierMath Tier 4	95.0% (best of these models)#6 of 70	46.3%#25 of 70
Arena math	1511 (best of these models)#8 of 396	1509#9 of 396
SimpleQA Verified	72.2%#4 of 86	Not tested
LiveBench agentic coding	71.7% (best of these models)#2 of 66	64.1%#9 of 66
CursorBench	57.8% (best of these models)#1 of 62	41.6%#22 of 62
LiveBench language	86.3% (best of these models)#10 of 66	82.8%#24 of 66
LiveBench instructions	67.0%#39 of 66	78.0% (best of these models)#4 of 66
Arena creative writing	1516 (best of these models)#2 of 411	1459#28 of 411
Arena instruction following	1517 (best of these models)#2 of 413	1486#16 of 413
LiveBench data analysis	80.3% (best of these models)#7 of 66	79.6%#12 of 66
LiveBench reasoning	92.2% (best of these models)#3 of 66	89.7%#15 of 66
GPQA Diamond	90.6%#40 of 319	Not tested
Arena hard prompts	1534 (best of these models)#2 of 413	1517#10 of 413
Chess puzzles	Not tested	38.0%#32 of 227
Price per million tokens
Input	$4.00	$1.25 (best of these models)
Output	$20.00	$4.25 (best of these models)
Blended, 3 input to 1 output	$8.00	$2.00 (best of these models)
Cached input	$0.20	$0.15 (best of these models)
Writing to the cache	$5.00	Not reported
The maker’s own price	This listing	Not sold directly
Limits
Context window	1M tokens	1M tokens
Max input	1M tokens	1M tokens
Max output	128K tokens	131.1K tokens (best of these models)
Features
Reads	images, PDFs and text	audio, images, PDFs, text and video
Produces	text	text
Reasoning	Yeseffort low, medium, high, xhigh, max; can be switched off	Yeseffort minimal, low, medium, high, xhigh
Tool calling	Yes	Yes
Structured output	Yes, such as JSON	Yes, such as JSON
File attachments	Yes	Yes
Temperature setting	Fixed by the provider	Supported

Bold marks the better value in each row. Prices are each model’s own list price, or the middle price across hosts when the maker does not sell it, blended as three input tokens for every output token. Test results as published by LiveBench (Apache-2.0), Epoch AI (CC BY 4.0), Cursor CursorBench, compiled by Epoch AI (CC BY 4.0), Arena (CC BY 4.0); model details and prices from models.dev (MIT). Confirm pricing with the provider before use.