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Model comparison

Claude Opus 5.5 vs Muse Spark 1.3

Anthropic against Meta, compared on context, price, and verified benchmark results.

Catalog record checked September 26, 2026Individual provider fields may changeEvidence confidence: High — see receipts below

Anthropic

Claude Opus 5.5

Frontier

vs

Meta

Muse Spark 1.3

Frontier

AI model capability comparison
SpecificationClaude Opus 5.5Muse Spark 1.3
ProviderAnthropicMeta
TierFrontierFrontier
Context window1MWinner: 1.05M
Max output128KWinner: 131K
Input / 1M tokens$4Winner: $1.25
Output / 1M tokens$20Winner: $4.25
WeightsClosedClosed
ParametersNot disclosedUnverifiedMeta frontier model
Reasoning levelsadaptiveminimal, low, medium, high, xhigh, max
Modalitiestext, imagetext, image, video, audio, pdf
API model idclaude-opus-5-5muse-spark-1.3
ReleasedSeptember 22, 2026September 2, 2026
Artificial Analysis Intelligence Index [max] (2026-09-26)Winner: 57.648.1
Humanity's Last Exam [max] (2026-09-26)61.4Not verifiedUnverified
Terminal-Bench 4.0 [max] (2026-09-26)59.6Not verifiedUnverified
Terminal-Bench 4.0 [xhigh] (2026-09-22)66.4Not verifiedUnverified
DeepSWE 1.1 (2026-09-02)Not verifiedUnverified75.4
Terminal-Bench 2.1 (2026-09-03)Not verifiedUnverified88.8

Prices are USD per million tokens at standard rates, excluding batch and caching discounts. Bold indicates the better figure where one is objectively better. Values we could not confirm from the provider are shown as “Not verified” rather than estimated.

Benchmark receipts

Where each score comes from, and how far it can be compared across models.

Pricing tiers

Claude Opus 5.5: $4/$20 per MTok, no long-context surcharge. Cache reads $0.20; 5-minute cache writes $5, 1-hour writes $8. Batch $2/$10; Fast mode $8/$40. Batches API allows 300K output with the output-300k-2026-03-24 beta header. Knowledge cutoff Jun 2026; retirement not before 2027-09-22.

Muse Spark 1.3: $1.25/$4.25 per MTok on Meta's Model API (Standard tier; cached input $0.15); a $0.10/$0.20 'contributor' tier applies when your data is used for training. Meta's pricing page lists no long-context premium and no scheduled price change.

FrontierRecord checked September 26, 2026

Claude Opus 5.5

Claude Opus 5.5 is Anthropic's default model for agentic coding and knowledge work — Anthropic says it performs near Fable 5.1 on most work at about 40% lower running cost than Opus 5, and it leads the Artificial Analysis Intelligence Index v4.3.2.

Best for

  • Complex agentic coding
  • Enterprise knowledge work
  • Default frontier model

Watch out

Breaking changes from Opus 5: adaptive thinking cannot be disabled (effort runs low to max, default medium) and forced tool use returns an error. Verbose at max effort, so cap output on cost-sensitive routes.

FrontierRecord checked September 26, 2026

Muse Spark 1.3

Muse Spark 1.3 is Meta's September 2026 frontier refresh — a self-reported DeepSWE 1.1 field leader at $1.25/$4.25, with a 1M-token context aimed at autonomous agent workflows.

Best for

  • Long-horizon coding agents
  • Frontier quality below frontier pricing
  • Meta ecosystem

Watch out

The headline 75.4% DeepSWE score comes from the 'max' thinking mode, which is not broadly available yet and is pending independent verification. The 131,072 output cap is per third-party API docs — Meta's own spec page does not publish it. Closed weights.

When the cheaper one wins

Muse Spark 1.3 is cheaper on output at $4.25 per million tokens against $20 for Claude Opus 5.5 — about 4.7×. Use the cheaper tier for classification, extraction, summarisation, and any task where the expensive model’s extra score does not change the accepted output. The expensive one only pays if your hardest task actually fails on the cheap tier. These are standard-tier API rates, excluding batch and cache discounts.

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Evidence confidence: High

How strong and complete the evidence behind this comparison is — not a prediction of which model is better.

  • Pricing verified on both sides — Input and output rates are verified for both models.
  • 4/5 core specs verified on both sides — Not published for at least one side: parameter count.
  • 1 shared named benchmark with differing scores — Measured on: Artificial Analysis Intelligence Index.
  • Verified within the last 90 days — Newest catalog check was 2 days ago.
  • Both models carry source citations — Each side has at least two catalog sources on record.

Source receipts

Each catalog figure was checked against the provider or an independent second source on the date shown.

Related comparisons

Diving deeper on one model? Claude Opus 5.5 · Muse Spark 1.3

Common questions

Claude Opus 5.5 vs Muse Spark 1.3

Answered from the verified figures on this page rather than general guidance.

Is Claude Opus 5.5 or Muse Spark 1.3 cheaper for input?
Muse Spark 1.3 is cheaper at $1.25 per million input tokens, against $4 for Claude Opus 5.5 — roughly 3.2× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; Claude Opus 5.5 has tiered pricing: $4/$20 per MTok, no long-context surcharge. Cache reads $0.20; 5-minute cache writes $5, 1-hour writes $8. Batch $2/$10; Fast mode $8/$40. Batches API allows 300K output with the output-300k-2026-03-24 beta header. Knowledge cutoff Jun 2026; retirement not before 2027-09-22. Muse Spark 1.3 has tiered pricing: $1.25/$4.25 per MTok on Meta's Model API (Standard tier; cached input $0.15); a $0.10/$0.20 'contributor' tier applies when your data is used for training. Meta's pricing page lists no long-context premium and no scheduled price change.
Is Claude Opus 5.5 or Muse Spark 1.3 cheaper for output?
Muse Spark 1.3 is cheaper at $4.25 per million output tokens, against $20 for Claude Opus 5.5 — roughly 4.7× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; Claude Opus 5.5 has tiered pricing: $4/$20 per MTok, no long-context surcharge. Cache reads $0.20; 5-minute cache writes $5, 1-hour writes $8. Batch $2/$10; Fast mode $8/$40. Batches API allows 300K output with the output-300k-2026-03-24 beta header. Knowledge cutoff Jun 2026; retirement not before 2027-09-22. Muse Spark 1.3 has tiered pricing: $1.25/$4.25 per MTok on Meta's Model API (Standard tier; cached input $0.15); a $0.10/$0.20 'contributor' tier applies when your data is used for training. Meta's pricing page lists no long-context premium and no scheduled price change.
Which has the larger context window, Claude Opus 5.5 or Muse Spark 1.3?
Muse Spark 1.3 accepts 1.05M tokens against 1M for Claude Opus 5.5. This only matters if you routinely send very long documents or large codebases.
Do Claude Opus 5.5 and Muse Spark 1.3 support the same reasoning levels?
Claude Opus 5.5 exposes adaptive, while Muse Spark 1.3 exposes minimal, low, medium, high, xhigh, max.
Should I use Claude Opus 5.5 or Muse Spark 1.3?
Both sit in the frontier tier, so the choice usually comes down to price and context rather than capability. Claude Opus 5.5 suits complex agentic coding; Muse Spark 1.3 suits long-horizon coding agents.

Next step

Choosing between them

The verified figures that separate this pair, computed from the catalog rather than restated boilerplate.

  • Input price: Muse Spark 1.3 costs $1.25 per 1M tokens versus $4 for Claude Opus 5.5 — a 3.2x difference at the headline tier.
  • Context: Muse Spark 1.3 takes 1.05M against 1M for Claude Opus 5.5 — only decisive if your prompts approach the smaller window.
  • Measured capability: Claude Opus 5.5 leads Artificial Analysis Intelligence Index 57.6 to 48.1 (measured 2026-09-26).
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