Is Claude Fable 5 good at Structured Output?
Claude Fable 5 ranks #68 of 113 for Structured Output — strong. The top pick for this task is GPT-5.4 Mini (max reasoning).
#68 / 113
Rank for this task
89.8
Score
$0.0291
Cost / run
Claude Fable 5 on each Structured Output sub-task
| Schema Adherence | 95.7/100 | #66 |
| Transformation | 92.9/100 | #68 |
| Missing & Ambiguous Data | 90.0/100 | #79 |
| Extraction | 87.9/100 | #66 |
| Noisy Structured Output Test | 80.0/100 | #78 |
Real examples, graded
WeakInvoice line items 0/100
“The response failed to follow strict JSON formatting by including markdown fences and wrapper text, and hallucinated data such as currency and subtotal.”
Frequently asked
Is Claude Fable 5 good at Structured Output?
Claude Fable 5 ranks #68 of 113 models we tested for Structured Output, scoring strong.
What is Claude Fable 5's strongest Structured Output skill?
Its best sub-task here is Schema Adherence.
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Prompt × model results
12 test cases · 3 evalsClaude Opus
GPT-5
Gemini
v1
7.1
6.8
7.4
v2
8.3
7.9
8.0
v3
9.2
★
8.6
8.4
Best combo: v3 × Claude Opus
9.2 quality · $0.004/run · 1.8s