STEALTHMARK · HEAD TO HEAD

All comparisons ↗

Claude Opus 5.5 vs Inkling-Small

Claude Opus 5.5 leads Inkling-Small by 45.0 points on StealthMark, 72.6 to 27.6. It leads on all 9 benchmarks. Claude Opus 5.5 scores higher on Newton's Mirror, with its largest category advantage in reflections.

See the difference ↘
All results ↗
All results ↗

Overall StealthMark

72.6/100Overall rank 2/53
27.6/100Overall rank 43/53

General Intelligence

71.3/100
25.5/100

Visual Intelligence

75.0/100
31.1/100

Reasoning efficiency

On every task, result quality and reasoning tokens are each compared with all measured models and weighed equally. Each dot is one model.

Single-step reasoning Result quality weighed against reasoning tokens on a single problem

Multi-step reasoning Result quality weighed against reasoning tokens across connected steps, as in agentic workflows

  • Claude Opus 5.5
  • Inkling-Small

Open or local

Open modelApache 2.0

BENCHMARK BY BENCHMARK

Where each model leads

  • Claude Opus 5.5
  • Inkling-Small
  • Other models
  • Median

DATASHEET

Specs and pricing

Both take about 1M tokens of context.

  • Claude Opus 5.5
  • Inkling-Small
  • Other models
  • Median
PricePer 1M output tokens, input below
Claude Opus 5.5: $20$4 inputInkling-Small: No list price
Context windowTokens per request, max output below
Claude Opus 5.5: 1MTied128K max outputInkling-Small: 1MTied
Output speedTokens per second, our measurement
Claude Opus 5.5: 166tokens/sInkling-Small: Not measured
SizeTotal and active parameters
Claude Opus 5.5: Not disclosedInkling-Small: 276B12B active
Developer
AnthropicThinking Machines Lab
Released
22 Sep 2026Not published
Origin
United StatesNot published
Input → output
Text, image → textText, image, audio → text
Architecture
Not published42-layer decoder-only transformer with sparse mixture-of-experts feed-forward (6 of 256 routed experts plus 2 shared per token); hybrid local and global attention; natively multimodal with a hierarchical patch image encoder and discrete-token audio

Full datasheets, every price and sourceClaude Opus 5.5 ↗Inkling-Small ↗

Anticipating threats and planning ahead. Collect coins while avoiding ghosts. Ghosts move before the player each turn, and collisions cost a life. 3 levels in sequence, up to 66 turns in total. Earlier moves and outcomes carry forward, testing learning across levels.

Claude Opus 5.5 66.3/100Rank 5/49

Survived 3 of 3
Foresight: complete playing field
Level 39 ptsTurn 20 / 20

Inkling-Small 30.2/100Rank 29/49

Survived 0 of 3
Foresight: complete playing field
Level 38 ptsTurn 17 / 20

Points per level

LevelClaude Opus 5.5Inkling-Small
Level 1Second Thoughts
27 ptsSurvived
9 ptsOut of lives
Level 2Pressure Pot
11 ptsSurvived
6 ptsOut of lives
Level 3Hide or Flight
9 ptsSurvived
8 ptsOut of lives

Cooperative planning and learning from experience. Coordinate two robots to push numbered cores onto matching sockets. Pressure plates hold doors open; moving either robot uses one turn. 5 levels in sequence, up to 152 turns in total. Earlier moves and outcomes carry forward, testing learning across levels.

Claude Opus 5.5 87.6/100Rank 1/50

Cleared 5 of 5
Latch: complete playing field
Level 520.6 ptsTurn 27 / 40

Inkling-Small 34.7/100Rank 34/50

Cleared 3 of 5
Latch: complete playing field
Level 518 ptsTurn 40 / 40

Points per level

LevelClaude Opus 5.5Inkling-Small
Level 1Hold the door
5.2 ptsCleared
5.2 ptsCleared
Level 2Crossfeed
10.2 ptsClearedFinished early · 1 beacon left
9.8 ptsCleared
Level 3Relay vault
19.2 ptsCleared
2.8 ptsFinished early
Level 4Passing bay
18.2 ptsClearedFinished early · 3 beacons left
8 ptsFinished early
Level 5Second thoughts
20.6 ptsCleared
18 ptsCleared

Newton's Mirror

Same task instructions

Physics, perspective and recursive reflections, tested together. Explore the test ↗

The judgment

Claude Opus 5.5

Open lateral sightlines, first reflected silhouettes and near-field planar panel placement are convincing. Missing outer chains, truncated repetitions and absent nested spherical room and emitter imagery remain the main weaknesses.

Inkling-Small

The sphere's apparent floor support, separate dark feature and broad paint ordering justify partial state credit. The major weakness is the largely missing mirror system: isolated side images and faint floor echoes do not establish repeated virtual rooms or curved spherical mapping. Downward framing, the oversized frontal panel, unresolved paint transport and satin surface appearance remain distinct limitations.

Score breakdown

CategoryClaude Opus 5.5Inkling-Small
State at 600 ms24.0/2514.0/25
Camera and placement15.0/153.0/15
Reflections55.0/1208.0/120
Materials and scale9.0/102.5/10
Floor-damage reward0.0/100.0/10

Benchmark task

A spinning metal sphere and paint in a mirrored room test physical reasoning, perspective and consistency across repeated reflections.

Selfie

Different task instructions

Visual construction and creative interpretation.

The judgment

Claude Opus 5.5

The centered coral squid has a friendly, restrained expression and a balanced radial silhouette within a cream arch. Smooth curves and soft shading give it an appealing matte finish. The mantle is more elongated than compact, the upper arms are visually ambiguous, and the two hanging tentacles read somewhat like legs. Clean execution supports a strong stylized illustration.

Inkling-Small

The faces and dripping caps communicate a cute mushroom scene, but simple construction and weak spatial relationships limit the result. The defining foot-stamping action is unresolved, the flattering portrait is smaller than its painter, and the requested material contrasts are only partly conveyed.

Score breakdown

CategoryClaude Opus 5.5Inkling-Small
Task & likeness8.0/102.5/10
Anatomy & construction7.5/101.5/10
Space & placement8.0/103.5/10
Light & reflections7.5/103.0/10
Purposeful detail7.0/104.5/10
Artistry & character7.0/103.0/10
Materials & effects7.0/103.5/10
Visual integrity8.5/102.0/10

Benchmark task

Claude Opus 5.5

A coral squid with spreading arms tests connected anatomy, balanced composition and soft surface shading.

Inkling-Small

Character scenes test expression, anatomy, materials and coherent visual construction.

Mona Lisa

Same task instructions

Precise visual recall and portrait reconstruction.

The judgment

Claude Opus 5.5

The portrait preserves the recognizable composition, dark veil, folded hands and distant landscape. Replication is limited by the elongated face and neck, conspicuous eyes and simplified smile. Hands remain connected but their rounded fingers and wrists lack convincing anatomy. Restrained colors create cohesion; shallow modeling and pervasive mottling weaken volume and painterly subtlety.

Inkling-Small

A recognizable but rudimentary Mona Lisa interpretation. Facial shading and subdued colors provide coherence, while the frontal blocklike torso, unresolved wrists, fingerless hands and shallow landscape substantially limit likeness, construction and finish.

Score breakdown

CategoryClaude Opus 5.5Inkling-Small
Task & likeness6.5/102.5/10
Anatomy & construction5.5/102.5/10
Space & placement6.5/103.0/10
Light & reflections6.5/102.5/10
Purposeful detail6.5/102.0/10
Artistry & character6.0/102.5/10
Materials & effects7.0/102.0/10
Visual integrity7.0/103.0/10

Benchmark task

An SVG interpretation of the Mona Lisa tests facial likeness, anatomy and the composition of a familiar portrait.

Beach

Same task instructions

Creativity, perspective and visual beauty.

The judgment

Claude Opus 5.5

A lively, well-composed beach illustration with rich sunset colors, recognizable animals and appealing accessories. The sun reflection establishes a strong central focus. Clean silhouettes and small details reward inspection, though simplified animal construction, uneven contact shadows and mostly flat materials limit depth and realism.

Inkling-Small

A recognizable sunset beach with a clear focal sun and appealing color transitions. Connected fish silhouettes and layered scenery establish basic coherence. Primitive figures, ambiguous recreation, sparse descriptive detail and weak grounding limit construction and depth. The aligned reflection supplies a useful lighting cue, but shadows and material effects remain underdeveloped.

Score breakdown

CategoryClaude Opus 5.5Inkling-Small
Task & likeness8.5/103.5/10
Anatomy & construction7.5/103.0/10
Space & placement7.0/103.0/10
Light & reflections7.5/103.0/10
Purposeful detail7.5/103.0/10
Artistry & character8.0/103.0/10
Materials & effects6.5/102.5/10
Visual integrity8.0/102.0/10

Benchmark task

A busy shoreline at sunset tests scene composition, animal forms and the relationship between light and water reflections.

Ground Truth

Same task instructions

Physical reasoning, light and visual reconstruction.

The judgment

Claude Opus 5.5

This benchmark has not been assessed yet.

Inkling-Small

This benchmark has not been assessed yet.

Benchmark task

A plank, computer mouse and blueberry in a steel room test physical stability, spatial relationships, materials and lighting.

Raccoon

Same task instructions

Scene composition and interacting subjects.

The judgment

Claude Opus 5.5

The masked raccoon clearly rides the dog's back, and the dog's forward paw reaches the steering grip. Expressive faces, vivid colors and sweeping wakes create an appealing illustration. Connected limbs remain schematic, as does the small steering assembly. The broad hull and flat foam weaken water contact; the glowing sun lacks a corresponding reflection or convincing cast shadows.

Inkling-Small

Recognizable animals, readable accessories and an appealing sunset support a coherent basic cartoon. Rounded construction leaves joints, riding support and steering unresolved. Decorative gradients contribute atmosphere, but directional lighting, distinct materials and convincing water displacement are weakly demonstrated.

Score breakdown

CategoryClaude Opus 5.5Inkling-Small
Task & likeness8.5/104.0/10
Anatomy & construction7.5/103.0/10
Space & placement7.5/104.0/10
Light & reflections6.0/105.0/10
Purposeful detail8.5/105.5/10
Artistry & character7.0/104.0/10
Materials & effects7.0/105.0/10
Visual integrity8.0/105.0/10

Benchmark task

A jet-ski scene pairs a canine driver with a raccoon passenger. It tests the placement and contact of interacting subjects, along with vehicle construction.

Pelican

Same task instructions

Subject construction and spatial relationships.

The judgment

Claude Opus 5.5

The recognizable pelican, orderly bicycle wheels and harmonious sunset create an appealing illustration. Both legs connect to the body and reach pedals; no clear detached or inverted parts appear. Steering contact and seating support are less convincing, while the drivetrain remains schematic. Crisp outlines give a clean finish, but limited shading and flat surfaces leave the scene with modest depth.

Inkling-Small

The pelican is immediately recognizable, and its sweeping neck, shaped bill and orderly spokes provide character. Riding remains only partially realized: legs, pedal engagement, steering and seat support cannot be read confidently. Controlled graphic effects add atmosphere, but simplified construction and weak grounding keep the result basic.

Score breakdown

CategoryClaude Opus 5.5Inkling-Small
Task & likeness8.5/104.0/10
Anatomy & construction8.0/103.0/10
Space & placement7.0/103.0/10
Light & reflections6.0/103.0/10
Purposeful detail8.0/104.5/10
Artistry & character7.5/105.0/10
Materials & effects6.0/104.5/10
Visual integrity8.5/103.0/10

Benchmark task

A cycling pelican tests anatomy, riding posture and contact between the bird and the bicycle.