STEALTHMARK · HEAD TO HEAD

All comparisons ↗

Claude Fable 5.2 vs Claude Sonnet 5.5

Claude Fable 5.2 leads Claude Sonnet 5.5 by 9.6 points on StealthMark, 79.8 to 70.2. It leads on 7 of 9 benchmarks, including both games, and Claude Sonnet 5.5 on 2. Claude Fable 5.2 scores higher on Newton's Mirror, with its largest category advantage in reflections.

See the difference ↘
All results ↗
All results ↗

Overall StealthMark

79.8/100Overall rank 1/57
70.2/100Overall rank 4/57

General Intelligence

81.7/100
67.0/100

Visual Intelligence

76.0/100
76.1/100

Reasoning efficiency

How many reasoning tokens a model needs for the quality it delivers.

Single-step reasoning How much it reasons to understand a task

Multi-step reasoning How much it keeps reasoning as a task goes on

  • Claude Sonnet 5.5

Cost efficiency

How much Performance you get for your money.

  • Claude Fable 5.2Not measured

BENCHMARK BY BENCHMARK

Where each model leads

  • Claude Fable 5.2
  • Claude Sonnet 5.5
  • Other models
  • Median

DATASHEET

Specs and pricing

  • Claude Fable 5.2
  • Claude Sonnet 5.5
  • Other models
  • Median
PricePer 1M output tokens, input below
Claude Fable 5.2: No list priceClaude Sonnet 5.5: $10$2 input
Context windowTokens per request, max output below
Claude Fable 5.2: Not publishedClaude Sonnet 5.5: 1M128K max output
Output speedTokens per second, our measurement
Claude Fable 5.2: Not measuredClaude Sonnet 5.5: 249tokens/s
Developer
Not publishedAnthropic
Released
Not published28 Sep 2026
Origin
Not publishedUnited States
Input → output
Not publishedText, image → text

Full datasheets, every price and sourceClaude Sonnet 5.5 ↗

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 Fable 5.2 77.2/100Rank 2/53

Survived 3 of 3
Foresight: complete playing field
Level 318 ptsTurn 20 / 20

Claude Sonnet 5.5 59.6/100Rank 13/53

Survived 2 of 3
Foresight: complete playing field
Level 310 ptsTurn 20 / 20

Points per level

LevelClaude Fable 5.2Claude Sonnet 5.5
Level 1Second Thoughts
27 ptsSurvived
25 ptsSurvived
Level 2Pressure Pot
12 ptsSurvived
10 ptsOut of lives
Level 3Hide or Flight
18 ptsSurvived
10 ptsSurvived

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 Fable 5.2 100.0/100Rank 1/54

Cleared 5 of 5
Latch: complete playing field
Level 520.8 ptsTurn 26 / 40

Claude Sonnet 5.5 83.9/100Rank 5/54

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

Points per level

LevelClaude Fable 5.2Claude Sonnet 5.5
Level 1Hold the door
5.2 ptsCleared
5.2 ptsCleared
Level 2Crossfeed
10.2 ptsClearedFinished early · 1 beacon left
10 ptsClearedFinished early · 1 beacon left
Level 3Relay vault
19.2 ptsCleared
19.2 ptsCleared
Level 4Passing bay
18.2 ptsClearedFinished early · 3 beacons left
18.2 ptsClearedFinished early · 3 beacons left
Level 5Second thoughts
20.8 ptsCleared
20.6 ptsCleared

Newton's Mirror

Same task instructions

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

The judgment

Claude Fable 5.2

The composition closely preserves the principal camera relationships. Visible cyan contact, elongated crimson coating and separate airborne black paint support the required interaction sequence, with a small crimson transport overshoot. Correct broad mirror placement coexists with major omissions in nested spherical imagery and simplified emitter mapping. Core score: 105.5/170; floor-damage reward: 0/10; combined total: 105.5/180.

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.

Score breakdown

CategoryClaude Fable 5.2Claude Sonnet 5.5
State at 600 ms24.0/2524.0/25
Camera and placement15.0/1515.0/15
Reflections80.0/12035.0/120
Materials and scale8.5/1010.0/10
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

Same task instructions

Visual construction and creative interpretation.

The judgment

Claude Fable 5.2

The compact mantle, eight curling rays and quiet face closely realize the requested living emblem. Controlled arm contours, coherent overlaps and restrained ornament give the design character. Shallow depth, ribbon-like arm modeling and repeated highlight bands limit anatomical and lighting complexity without compromising the intact silhouette.

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.

Score breakdown

CategoryClaude Fable 5.2Claude Sonnet 5.5
Task & likeness9.0/108.0/10
Anatomy & construction7.5/108.0/10
Space & placement7.0/108.0/10
Light & reflections7.0/107.5/10
Purposeful detail6.5/108.0/10
Artistry & character6.5/108.0/10
Materials & effects7.0/108.0/10
Visual integrity8.5/108.5/10

Benchmark task

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

Mona Lisa

Different task instructions

Precise visual recall and portrait reconstruction.

The judgment

Claude Fable 5.2

A developed illustrative portrait with controlled facial shading, connected limbs, layered scenery and distinct aged-paint and gold effects. Its frontal torso, conspicuous smile and flattened fingers limit replication and anatomical precision. Decorative finish is stronger than the underlying seated construction.

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.

Score breakdown

CategoryClaude Fable 5.2Claude Sonnet 5.5
Task & likeness6.5/106.5/10
Anatomy & construction6.0/105.0/10
Space & placement6.0/106.0/10
Light & reflections6.5/106.5/10
Purposeful detail6.0/106.0/10
Artistry & character6.5/106.5/10
Materials & effects7.5/106.0/10
Visual integrity7.5/106.5/10

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 Fable 5.2

A lively sunset beach with clear playful activity, purposeful small details and developed water reflections. Layering and supported placements hold the scene together. Schematic anatomy and the turtle's overhead viewpoint limit construction, space and artistry, while atmospheric and surface effects show greater refinement.

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.

Score breakdown

CategoryClaude Fable 5.2Claude Sonnet 5.5
Task & likeness9.0/109.0/10
Anatomy & construction8.0/108.0/10
Space & placement7.5/108.5/10
Light & reflections8.5/108.5/10
Purposeful detail8.5/109.5/10
Artistry & character8.0/109.5/10
Materials & effects7.5/108.5/10
Visual integrity8.0/108.0/10

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 Fable 5.2

This benchmark has not been assessed yet.

Claude Sonnet 5.5

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 Fable 5.2

A controlled action illustration with expressive animals, demonstrated riding and steering, and an energetic layered wake. Purposeful small features and articulated poses strengthen the drawing. Simplified extremities, shallow character volume and limited physical lighting remain its principal constraints.

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.

Score breakdown

CategoryClaude Fable 5.2Claude Sonnet 5.5
Task & likeness8.5/108.5/10
Anatomy & construction8.0/107.0/10
Space & placement7.5/108.0/10
Light & reflections7.0/106.5/10
Purposeful detail8.5/108.0/10
Artistry & character8.0/107.0/10
Materials & effects7.5/107.5/10
Visual integrity8.0/108.0/10

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 Fable 5.2

A strong illustration with an expressive pelican, readable riding contacts and carefully constructed bicycle details. Layered plumage, basket weave and coastal scenery reward inspection. Continuous attachments support the action, while limited visible leg articulation, modest volume and weakly directional foreground lighting constrain physical sophistication.

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.

Score breakdown

CategoryClaude Fable 5.2Claude Sonnet 5.5
Task & likeness9.0/109.0/10
Anatomy & construction8.0/107.5/10
Space & placement7.5/107.5/10
Light & reflections6.5/106.5/10
Purposeful detail8.0/108.0/10
Artistry & character7.5/107.5/10
Materials & effects7.0/106.5/10
Visual integrity8.0/108.0/10

Benchmark task

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