Model A

Anthropic

—

Evidence status unavailable

90% interval unavailable

Claude Mythos 5.1 vs Muse Spark

Updated September 1, 2026. Public scores include evidence status and uncertainty. They are not guarantees for a specific workload.

Model B

Muse Spark

Which one for your work

Recommendations appear only when a shared evidence basis or an explicit operating constraint supports the call. Secondary and unsupported use cases stay disclosed below the initial list.

Long documents
Prompts that approach the documented context limit
Claude Mythos 5.1
Claude Mythos 5.1 has the larger documented context window.
Confidence: documented

Show secondary and unsupported calls

Coding work
Code generation, repair, and software-engineering tasks
Not enough matched evidence
No shared weighted benchmark basis supports a winner.
Confidence: limited
Agentic work
Tool use, computer use, and multi-step task completion
Not enough matched evidence
No shared weighted benchmark basis supports a winner.
Confidence: limited
Chat turn cost
1K fresh input + 500 output tokens
Not enough matched evidence
A complete comparable API-rate estimate is not available for both models.
Confidence: listed-rates
Cache-heavy agent loop cost
200K cached + 20K fresh input + 10K output tokens
Not enough matched evidence
A complete comparable API-rate estimate is not available for both models.
Confidence: listed-rates
Repository review cost
50K fresh input + 3K output tokens
Not enough matched evidence
A complete comparable API-rate estimate is not available for both models.
Confidence: listed-rates

What is actually comparable

Shared results can support a head-to-head reading. Results present for only one model describe coverage, not superiority.

1 Claude Mythos 5.1 only

24 Muse Spark only

Shared results: 0
Claude Mythos 5.1 only: 1
Muse Spark only: 24
Like-for-like categories: 0 / 8

Category results, on a stated basis

Each row states whether both averages use the same weighted benchmark set. Directional and not-comparable rows remain visible, but they never receive a winner in this template.

Agentic

Not comparable

Claude Mythos 5.1: Not measured
Muse Spark: 59.0
Weighted basis: 0 vs 1 rows
Reading: Not comparable

Coding

Not comparable

Claude Mythos 5.1: Not measured
Muse Spark: 67.8
Weighted basis: 0 vs 2 rows
Reading: Not comparable

Reasoning

Not comparable

Claude Mythos 5.1: Not measured
Muse Spark: 42.5
Weighted basis: 0 vs 1 rows
Reading: Not comparable

Knowledge

Not comparable

Claude Mythos 5.1: Not measured
Muse Spark: 50.4
Weighted basis: 0 vs 1 rows
Reading: Not comparable

Math

Not comparable

Claude Mythos 5.1: Not measured
Muse Spark: 32.9
Weighted basis: 0 vs 2 rows
Reading: Not comparable

Multilingual

Not comparable

Claude Mythos 5.1: Not measured
Muse Spark: Not measured
Weighted basis: 0 vs 0 rows
Reading: Not comparable

Multimodal

Not comparable

Claude Mythos 5.1: Not measured
Muse Spark: 82.5
Weighted basis: 0 vs 2 rows
Reading: Not comparable

Instruction following

Not comparable

Claude Mythos 5.1: Not measured
Muse Spark: Not measured
Weighted basis: 0 vs 0 rows
Reading: Not comparable

Category averages with the server-provided evidence basis for Claude Mythos 5.1 and Muse Spark
Category	Claude Mythos 5.1	Muse Spark	Weighted basis	Reading
Agentic	Not measured	59.0	Not comparable0 vs 1 rows	Not comparable
Coding	Not measured	67.8	Not comparable0 vs 2 rows	Not comparable
Reasoning	Not measured	42.5	Not comparable0 vs 1 rows	Not comparable
Knowledge	Not measured	50.4	Not comparable0 vs 1 rows	Not comparable
Math	Not measured	32.9	Not comparable0 vs 2 rows	Not comparable
Multilingual	Not measured	Not measured	Not comparable0 vs 0 rows	Not comparable
Multimodal	Not measured	82.5	Not comparable0 vs 2 rows	Not comparable
Instruction following	Not measured	Not measured	Not comparable0 vs 0 rows	Not comparable

Shape of the matched evidence

Only shared public evidence is shown. Sparse evidence stays a ruled list rather than being closed into a radar shape.

A shared-evidence shape is not available.

BenchLM does not draw a radar or infer missing axes when the matched evidence is too sparse.

What each workload costs

Three fixed token mixes turn per-token rates into comparable decisions. Each scenario states context fit and whether cached input had to fall back to the published list-input rate.

Chat turn

1K fresh input + 500 output tokens

Claude Mythos 5.1: API rate not published; Fits in one request
Muse Spark: API rate not published; Fits in one request

Claude Mythos 5.1 has no comparable published API token rate. Muse Spark has no comparable published API token rate.

Repository review

50K fresh input + 3K output tokens

Claude Mythos 5.1: API rate not published; Fits in one request
Muse Spark: API rate not published; Fits in one request

Claude Mythos 5.1 has no comparable published API token rate. Muse Spark has no comparable published API token rate.

Cache-heavy agent loop

200K cached + 20K fresh input + 10K output tokens

Claude Mythos 5.1: API rate not published; Fits in one request; Cached-input rate unavailable
Muse Spark: API rate not published; Fits in one request; Cached-input rate unavailable

Claude Mythos 5.1 has no comparable published API token rate. Muse Spark has no comparable published API token rate.

Specification differences

Sourced differences are shown directly. Missing facts stay explicit instead of being inferred from a model name or family.

SpecificationClaude Mythos 5.1Muse Spark

Context window

Maximum documented context; output-token limits may be lower.

Claude Mythos 5.1

Claude Fable 5.1 and Claude Mythos 5.1 system card

Muse Spark

262K

API model ID

Claude Mythos 5.1

Not sourced

Muse Spark

Not sourced

Cached-input rate

A missing cached-input rate falls back to the listed input rate only in the stated workload estimate.

Claude Mythos 5.1

No comparable hosted API rate

Anthropic Fable 5.1 and Mythos 5.1 launch

Muse Spark

No comparable hosted API rate

Documented inputs

Claude Mythos 5.1

Not sourced

Muse Spark

Not sourced

Documented outputs

Claude Mythos 5.1

Not sourced

Muse Spark

Not sourced

Provider availability

Claude Mythos 5.1

Limited Access · Cyber Verification Program, Life Sciences Verification Program, Claude Security

Anthropic Fable 5.1 and Mythos 5.1 launch

Muse Spark

Not sourced

Reasoning profile

Claude Mythos 5.1

Reasoning

Muse Spark

Reasoning

Weight access

Claude Mythos 5.1

Proprietary

Muse Spark

Proprietary

License

Claude Mythos 5.1

Proprietary

Muse Spark

Proprietary

Release date

Claude Mythos 5.1

2026-09-01

Muse Spark

2026-04-08

If you already use one of these models

Deployment change: The models list different providers, so authentication, endpoint behavior, limits, and feature support may change.
Quality signal: The public evidence has no benchmark result shared by both models, so it does not support a quality verdict.
Workload cost: A complete comparable API-rate estimate is not available for both models.
Context tradeoff: Claude Mythos 5.1 has the larger documented window (1M).

Run the same representative tasks against both endpoints before changing production traffic.

Benchmark evidence

The full public result ledger is available for audit without forcing a wide desktop table onto a phone.

Browse raw public benchmark evidence25 rows

Agentic

Terminal-Bench 4.0
Claude Mythos 5.160.90%
Source
Muse Spark—
Not directly comparable
Terminal-Bench 2.0
Claude Mythos 5.1—
Muse Spark59%
Source
Not directly comparable
τ²-bench results
Claude Mythos 5.1—
Muse Spark91.5%
Source
Not directly comparable
DeepSearchQA
Claude Mythos 5.1—
Muse Spark74.8%
Source
Not directly comparable
CyberGym
Claude Mythos 5.1—
Muse Spark43.5%
Source
Not directly comparable
Claw-Eval
Claude Mythos 5.1—
Muse Spark63.8%
Source
Not directly comparable

Coding

SWE-bench Verified
Claude Mythos 5.1—
Muse Spark77.4%
Source
Not directly comparable
SWE-bench Pro
Claude Mythos 5.1—
Muse Spark52.4%
Source
Not directly comparable
LiveCodeBench Pro
Claude Mythos 5.1—
Muse Spark80.0%
Source
Not directly comparable
Vibe Code Bench
Claude Mythos 5.1—
Muse Spark19.67%
Source
Not directly comparable

Reasoning

ARC-AGI-2
Claude Mythos 5.1—
Muse Spark42.5%
Source
Not directly comparable

Knowledge

GPQA-D
Claude Mythos 5.1—
Muse Spark89.5%
Source
Not directly comparable
HLE
Claude Mythos 5.1—
Muse Spark50.4%
Source
Not directly comparable
HLE w/o tools
Claude Mythos 5.1—
Muse Spark42.8%
Source
Not directly comparable
HealthBench Hard
Claude Mythos 5.1—
Muse Spark42.8%
Source
Not directly comparable
MedXpertQA (Text)
Claude Mythos 5.1—
Muse Spark52.6%
Source
Not directly comparable

Math

FrontierMath v2 (Tiers 1-3)
Claude Mythos 5.1—
Muse Spark39.000%
Source
Not directly comparable
FrontierMath v2 (Tier 4)
Claude Mythos 5.1—
Muse Spark14.600%
Source
Not directly comparable

Multimodal

CharXiv
Claude Mythos 5.1—
Muse Spark86.4%
Source
Not directly comparable
MMMU-Pro
Claude Mythos 5.1—
Muse Spark80.4%
Source
Not directly comparable
ERQA
Claude Mythos 5.1—
Muse Spark64.7%
Source
Not directly comparable
SimpleVQA
Claude Mythos 5.1—
Muse Spark71.3%
Source
Not directly comparable
ScreenSpot Pro
Claude Mythos 5.1—
Muse Spark84.1%
Source
Not directly comparable
ZeroBench
Claude Mythos 5.1—
Muse Spark33.0%
Source
Not directly comparable
MedXpertQA (MM)
Claude Mythos 5.1—
Muse Spark78.4%
Source
Not directly comparable

Frequently asked questions

Which is better, Claude Mythos 5.1 or Muse Spark?

The public evidence has no benchmark result shared by both models, so it does not support a quality verdict. The page therefore keeps the decision tied to the specific documented workload.

Which is better for coding, Claude Mythos 5.1 or Muse Spark?

The published evidence does not provide a shared weighted coding basis for both models, so BenchLM does not name a coding winner.

Which is better for agentic tasks, Claude Mythos 5.1 or Muse Spark?

The published evidence does not provide a shared weighted agentic tasks basis for both models, so BenchLM does not name a agentic tasks winner.

Which costs less, Claude Mythos 5.1 or Muse Spark?

Both models do not have comparable published API token rates, so this page does not name a universal price winner.

Which has the larger context window, Claude Mythos 5.1 or Muse Spark?

Claude Mythos 5.1 has the larger documented context window: 1M, compared with 262K.

Related comparisons

Compare API pricing Read the methodology Open the model selector

Last updated September 1, 2026

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Claude Mythos 5.1 vs Muse Spark

Which one for your work

Long documents

Coding work

Agentic work

Chat turn cost

Cache-heavy agent loop cost

Repository review cost

What is actually comparable

Category results, on a stated basis

Agentic

Coding

Reasoning

Knowledge

Math

Multilingual

Multimodal

Instruction following

Shape of the matched evidence

What each workload costs

Chat turn

Repository review

Cache-heavy agent loop

Specification differences

Context window

API model ID

Cached-input rate

Documented inputs

Documented outputs

Provider availability

Reasoning profile

Weight access

License

Release date

Benchmark evidence

Agentic

Coding

Reasoning

Knowledge

Math

Multimodal

Frequently asked questions

Which is better, Claude Mythos 5.1 or Muse Spark?

Which is better for coding, Claude Mythos 5.1 or Muse Spark?

Which is better for agentic tasks, Claude Mythos 5.1 or Muse Spark?

Which costs less, Claude Mythos 5.1 or Muse Spark?

Which has the larger context window, Claude Mythos 5.1 or Muse Spark?

Related comparisons

Watch Claude Mythos 5.1 vs Muse Spark