# Mellum2-12B-A2.5B-Thinking vs Muse Spark

> Side-by-side benchmark comparison for Mellum2-12B-A2.5B-Thinking and Muse Spark across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/mellum2-12b-a2-5b-thinking-vs-muse-spark
- Last updated: September 4, 2026

- Shared sourced benchmarks: 1
- HTML indexing: indexable
- Ranking lane: BenchAlign v5

## Quick Verdict

Evidence is too thin for a benchmark verdict: Mellum2-12B-A2.5B-Thinking and Muse Spark share only 1 sourced benchmark row.

## Summary

- Only 1 shared sourced benchmark row is available. That is not enough for a broad capability verdict, so this mirror does not name an overall winner.
- Muse Spark has the larger published context window at 262K.

## Model Snapshot

| Property | Mellum2-12B-A2.5B-Thinking | Muse Spark |
|----------|----------|----------|
| Creator | JetBrains | Meta |
| Type | Open Weight | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 128K | 262K |
| Independent public score (not head-to-head) | null | 68.39 |
| Benchmarks Covered | 6 | 24 |
| Pricing (input/output) | N/A | N/A |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- Mellum2-12B-A2.5B-Thinking public-lane score: 48.3 (Estimated · #76/151)
- Muse Spark public-lane score: 58.8 (Supported · #31/151)

| Benchmark | Mellum2-12B-A2.5B-Thinking | Muse Spark | Winner |
|-----------|-----------|-----------|--------|
| BFCL v4 | 45.6% | Coming soon | Coming soon |
| Terminal-Bench 2.0 | Coming soon | 59% | Coming soon |
| τ²-bench results | Coming soon | 91.5% | Coming soon |
| DeepSearchQA | Coming soon | 74.8% | Coming soon |
| CyberGym | Coming soon | 43.5% | Coming soon |
| Claw-Eval | Coming soon | 63.8% | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- Mellum2-12B-A2.5B-Thinking public-lane score: Coming soon
- Muse Spark public-lane score: 59.2 (Supported · #28/183)

| Benchmark | Mellum2-12B-A2.5B-Thinking | Muse Spark | Winner |
|-----------|-----------|-----------|--------|
| LiveCodeBench v6 | 69.9% | Coming soon | Coming soon |
| SWE-bench Verified | Coming soon | 77.4% | Coming soon |
| SWE-bench Pro | Coming soon | 52.4% | Coming soon |
| LiveCodeBench Pro | Coming soon | 80.0% | Coming soon |
| Vibe Code Bench | Coming soon | 19.67% | Coming soon |

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- Mellum2-12B-A2.5B-Thinking public-lane score: Coming soon
- Muse Spark public-lane score: 77.5 (#14/48)

| Benchmark | Mellum2-12B-A2.5B-Thinking | Muse Spark | Winner |
|-----------|-----------|-----------|--------|
| CharXiv | Coming soon | 86.4% | Coming soon |
| MMMU-Pro | Coming soon | 80.4% | Coming soon |
| ERQA | Coming soon | 64.7% | Coming soon |
| SimpleVQA | Coming soon | 71.3% | Coming soon |
| ScreenSpot Pro | Coming soon | 84.1% | Coming soon |
| ZeroBench | Coming soon | 33.0% | Coming soon |
| MedXpertQA (MM) | Coming soon | 78.4% | Coming soon |

### Reasoning

- Winner: Insufficient shared evidence
- Mellum2-12B-A2.5B-Thinking public-lane score: Coming soon
- Muse Spark public-lane score: 45.9 (Unranked · 3 rankable rows)

| Benchmark | Mellum2-12B-A2.5B-Thinking | Muse Spark | Winner |
|-----------|-----------|-----------|--------|
| ARC-AGI-2 | Coming soon | 42.5% | Coming soon |

### Knowledge

- Winner: Insufficient shared evidence
- Mellum2-12B-A2.5B-Thinking public-lane score: 48.8 (Estimated · #96/181)
- Muse Spark public-lane score: 65.7 (Supported · #23/181)

| Benchmark | Mellum2-12B-A2.5B-Thinking | Muse Spark | Winner |
|-----------|-----------|-----------|--------|
| MMLU-Redux | 86.2% | Coming soon | Coming soon |
| GPQA | 57.6% | Coming soon | Coming soon |
| GPQA-D | 57.6% | 89.5% | Muse Spark |
| HLE | Coming soon | 50.4% | Coming soon |
| HLE w/o tools | Coming soon | 42.8% | Coming soon |
| HealthBench Hard | Coming soon | 42.8% | Coming soon |
| MedXpertQA (Text) | Coming soon | 52.6% | Coming soon |

### Instruction Following

- Winner: Insufficient shared evidence
- Mellum2-12B-A2.5B-Thinking public-lane score: Coming soon
- Muse Spark public-lane score: 92.9 (#8/120)

| Benchmark | Mellum2-12B-A2.5B-Thinking | Muse Spark | Winner |
|-----------|-----------|-----------|--------|
| IFEval | 76.5% | Coming soon | Coming soon |

### Mathematics

- Winner: Insufficient shared evidence
- Mellum2-12B-A2.5B-Thinking public-lane score: Coming soon
- Muse Spark public-lane score: 55.3 (Unranked · 2 rankable rows)

| Benchmark | Mellum2-12B-A2.5B-Thinking | Muse Spark | Winner |
|-----------|-----------|-----------|--------|
| FrontierMath v2 (Tiers 1-3) | Coming soon | 39.000% | Coming soon |
| FrontierMath v2 (Tier 4) | Coming soon | 14.600% | Coming soon |

## FAQ

### Is there enough evidence to pick between Mellum2-12B-A2.5B-Thinking and Muse Spark?

Not yet. The models share only 1 sourced benchmark row, so this mirror reports the available measurements and metadata without naming a broad winner.

### What can I compare safely on this page?

Published pricing, context windows, model type, and individual shared benchmark rows are directly comparable. Independent overall scores and non-overlapping benchmark coverage are labeled separately and should not be read as a controlled head-to-head result.

## Related Comparisons

- [Mellum2-12B-A2.5B-Thinking vs Mellum2-12B-A2.5B-Instruct](/compare/mellum2-12b-a2-5b-instruct-vs-mellum2-12b-a2-5b-thinking)
- [Muse Spark vs Mellum2-12B-A2.5B-Instruct](/compare/mellum2-12b-a2-5b-instruct-vs-muse-spark)
- [Mellum2-12B-A2.5B-Thinking vs Muse Spark 1.2](/compare/mellum2-12b-a2-5b-thinking-vs-muse-spark-1-2)
- [Muse Spark vs Muse Spark 1.2](/compare/muse-spark-vs-muse-spark-1-2)

## Explore More

- [Mellum2-12B-A2.5B-Thinking profile](/models/mellum2-12b-a2-5b-thinking)
- [Muse Spark profile](/models/muse-spark)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)