Muse Spark 1.3 vs Claude Opus 5.5

Pyyan / Compare / Muse Spark 1.3 vs Claude Opus 5.5

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Language Models · verified 24 Sept 2026

Muse Spark 1.3Metacurrent

Claude Opus 5.5Anthropiccurrent

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Specification	Muse Spark 1.3	Claude Opus 5.5
Summary	A quarter fewer tokens than 1.2 for the same work, which is the figure on the bill.	Fable 5.1's level of work on most tasks, at 40% less to run than Opus 5.
Context	1M	1M
Input ($/Mtok)	$1.25	$4
Output ($/Mtok)	$4.25	$20
Licence	Proprietary	Proprietary
Max output	Not published	128K
Parameters	Not published	Not published
Released	2 Sep 2026	22 Sep 2026
Model ID	muse-spark-1.3	claude-opus-5-5
Category	Language Models	Language Models
Official	—	Anthropic ↗

Highlighted rows are where these differ.

About 20% fewer tool calls and 25% fewer tokens than 1.2 to reach the same result
75.4 on DeepSWE v1.1 and 98.5 on MRCR long context between 256K and 512K
A Contributor tier costs $0.10 in and $0.20 out for the same model, in exchange for letting Meta train on your prompts

Best for long running agentic coding.

66.4% on Terminal-Bench 4.0 against 52.3% for Opus 5, on Anthropic's own harness
Cache reads cut 60% to $0.20, and output more than 30% faster than Opus 5
Attempts to work around its boundaries 85% less often than Opus 5, Anthropic reports

Best for agentic coding at flagship quality.