Claude Sonnet 5.5 59.6/100Rank 11/49

STEALTHMARK · HEAD TO HEAD
All comparisons ↗Claude Sonnet 5.5 leads Step 5 Preview by 31.2 points on StealthMark, 70.2 to 39.0. It leads on all 9 benchmarks. Claude Sonnet 5.5 scores higher on Beach, with its largest category advantage in anatomy & construction.
See the difference ↘On every task, result quality and reasoning tokens are each compared with all measured models and weighed equally. Each dot is one model.
BENCHMARK BY BENCHMARK
DATASHEET
Both take about 1M tokens of context.
Full datasheets, every price and sourceClaude Sonnet 5.5 ↗Step 5 Preview ↗
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.


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.


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


Claude Sonnet 5.5
The near-field silhouettes, broad perspective and paint contact order are recognizable. Missing outer chains, truncated repetitions and absent ordered imagery within the main and reflected spheres substantially limit the reflection system. Sparse spherical highlights leave much of the curved room and emitter mapping unsupported, despite some plausible planar light sequences.
Step 5 Preview
The main sphere, airborne black and small colored features occupy broadly appropriate positions. Most of the defining mirror system is absent, and paint interaction remains only partially supported. The small paint features do not visibly establish a separate volume-scale violation.
| Category | Claude Sonnet 5.5 | Step 5 Preview |
|---|---|---|
| State at 600 ms | 24.0/25 | 20.0/25 |
| Camera and placement | 15.0/15 | 13.5/15 |
| Reflections | 35.0/120 | 20.0/120 |
| Materials and scale | 10.0/10 | 7.0/10 |
| Floor-damage reward | 0.0/10 | 0.0/10 |
A spinning metal sphere and paint in a mirrored room test physical reasoning, perspective and consistency across repeated reflections.
Visual construction and creative interpretation.


Claude Sonnet 5.5
The centered coral squid has a friendly, composed expression and a balanced flower-like silhouette. Eight thick arms and two slender tentacles remain visibly connected, with no inverted parts. The mantle is elongated rather than compact, and the arm spacing is uneven. Soft shading gives volume, but dense stippling weakens the requested smooth matte finish; the broad background halo makes depth less precise.
Step 5 Preview
A charming diagonal climber and warm palette communicate the central idea. Simple rounded construction, crowded limb counting, uncertain footholds and an unattached upper shelf limit its physical coherence. Growth bands and the yarn trail add specificity, but the requested material distinctions and unravelled bootie remain underdeveloped.
| Category | Claude Sonnet 5.5 | Step 5 Preview |
|---|---|---|
| Task & likeness | 8.0/10 | 6.0/10 |
| Anatomy & construction | 8.0/10 | 4.5/10 |
| Space & placement | 8.0/10 | 5.0/10 |
| Light & reflections | 7.5/10 | 5.5/10 |
| Purposeful detail | 8.0/10 | 5.5/10 |
| Artistry & character | 8.0/10 | 5.0/10 |
| Materials & effects | 8.0/10 | 6.0/10 |
| Visual integrity | 8.5/10 | 5.0/10 |
Claude Sonnet 5.5
A coral squid with spreading arms tests connected anatomy, balanced composition and soft surface shading.
Step 5 Preview
Character scenes test expression, anatomy, materials and coherent visual construction.
Precise visual recall and portrait reconstruction.


Claude Sonnet 5.5
The crossed hands, dark dress, restrained smile and winding landscape clearly recall the Mona Lisa. Replication is limited by the frontal symmetry, wide eyes, elongated neck and flattened fingers. Soft facial shading provides volume, but heavy darkness and pervasive crackle obscure forms. The composition is coherent; the landscape and fabric remain visibly schematic.
Step 5 Preview
A recognizable, coherent simplification with purposeful facial contours and differentiated fingers. These provide more construction and detail than the broad silhouette alone suggests. The oversized face, frontal seated pose, unresolved wrists and sparse landscape still substantially limit likeness, depth and finish.
| Category | Claude Sonnet 5.5 | Step 5 Preview |
|---|---|---|
| Task & likeness | 6.5/10 | 4.0/10 |
| Anatomy & construction | 5.0/10 | 4.0/10 |
| Space & placement | 6.0/10 | 4.0/10 |
| Light & reflections | 6.5/10 | 3.5/10 |
| Purposeful detail | 6.0/10 | 4.0/10 |
| Artistry & character | 6.5/10 | 4.0/10 |
| Materials & effects | 6.0/10 | 3.0/10 |
| Visual integrity | 6.5/10 | 3.5/10 |
An SVG interpretation of the Mona Lisa tests facial likeness, anatomy and the composition of a familiar portrait.
Creativity, perspective and visual beauty.


Claude Sonnet 5.5
A richly designed beach illustration combines radiant sunset bands, intricate palm fans and playful silhouettes within a cohesive purple, coral and turquoise palette. Carefully varied accessories reward close inspection, while overlapping foreground forms and shoreline layers organize the abundant activity. Dense palm strokes compete with focal subjects; animal anatomy, relative scales and reflected silhouettes remain simplified.
Step 5 Preview
A recognizable sunset beach with clear warm-cool contrast and playful accessories. Basic animal construction, shallow foreground placement and schematic reflections limit spatial and physical credibility. Sparse descriptive detail and abruptly ended sky bands constrain the finish.
| Category | Claude Sonnet 5.5 | Step 5 Preview |
|---|---|---|
| Task & likeness | 9.0/10 | 4.0/10 |
| Anatomy & construction | 8.0/10 | 3.0/10 |
| Space & placement | 8.5/10 | 3.5/10 |
| Light & reflections | 8.5/10 | 3.5/10 |
| Purposeful detail | 9.5/10 | 3.0/10 |
| Artistry & character | 9.5/10 | 3.0/10 |
| Materials & effects | 8.5/10 | 3.5/10 |
| Visual integrity | 8.0/10 | 4.0/10 |
A busy shoreline at sunset tests scene composition, animal forms and the relationship between light and water reflections.
Physical reasoning, light and visual reconstruction.


Claude Sonnet 5.5
This benchmark has not been assessed yet.
Step 5 Preview
This benchmark has not been assessed yet.
A plank, computer mouse and blueberry in a steel room test physical stability, spatial relationships, materials and lighting.
Scene composition and interacting subjects.


Claude Sonnet 5.5
The raccoon clearly rides on the dog's back while the dog grips the jet ski controls. Expressive faces, vivid colors and a sweeping wake make the scene appealing. Visible limbs connect coherently, but overlapping steering paws and an indistinct control mounting weaken construction. Flat character lighting and simplified water limit depth and material realism.
Step 5 Preview
Recognizable animals, a bright palette and identifying accessories support a basic cartoon. Primitive anatomy, partial seated support, unresolved steering and weak hull-water contact limit the central action. Lighting and spray provide atmosphere without establishing convincing physical depth.
| Category | Claude Sonnet 5.5 | Step 5 Preview |
|---|---|---|
| Task & likeness | 8.5/10 | 4.0/10 |
| Anatomy & construction | 7.0/10 | 4.5/10 |
| Space & placement | 8.0/10 | 3.0/10 |
| Light & reflections | 6.5/10 | 3.5/10 |
| Purposeful detail | 8.0/10 | 4.0/10 |
| Artistry & character | 7.0/10 | 3.5/10 |
| Materials & effects | 7.5/10 | 3.0/10 |
| Visual integrity | 8.0/10 | 3.0/10 |
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.
Subject construction and spatial relationships.


Claude Sonnet 5.5
The pelican is immediately recognizable, with an expressive face, generous bill and appealing cycling pose. Spokes, chain, feathers and scarf provide purposeful detail. The bicycle largely holds together, though overlapping angular legs obscure the far foot’s pedal contact. Clean outlines and balanced composition succeed; flat surfaces and limited directional lighting constrain depth.
Step 5 Preview
The pelican and bicycle are recognizable, with a pleasant palette and basic diffuse shading. The riding relationship fails physically: the bird is unsupported, the front wheel is unmounted, and pedalling is unresolved. Simple geometric construction and sparse material treatment further limit the drawing.
| Category | Claude Sonnet 5.5 | Step 5 Preview |
|---|---|---|
| Task & likeness | 9.0/10 | 3.0/10 |
| Anatomy & construction | 7.5/10 | 3.0/10 |
| Space & placement | 7.5/10 | 3.0/10 |
| Light & reflections | 6.5/10 | 3.0/10 |
| Purposeful detail | 8.0/10 | 4.0/10 |
| Artistry & character | 7.5/10 | 3.0/10 |
| Materials & effects | 6.5/10 | 3.0/10 |
| Visual integrity | 8.0/10 | 2.0/10 |
A cycling pelican tests anatomy, riding posture and contact between the bird and the bicycle.