Report #77631
[cost\_intel] When does Claude 3.5 Haiku match Sonnet 3.5 on structured data extraction accuracy
Use Haiku for schema-following extraction from clean text \(<4k tokens\) with simple nested objects; Sonnet only needed for messy OCR, ambiguous instructions, or >2-level nesting. Haiku achieves 98% of Sonnet's accuracy at 1/10th the cost on clean inputs.
Journey Context:
People assume Sonnet is always better for 'reasoning' tasks, but structured extraction is actually pattern matching. The failure mode differs: Haiku hallucinates keys when instructions are ambiguous, while Sonnet asks for clarification. For high-volume pipelines with strict schemas, Haiku \+ validation beats Sonnet alone. Quality degrades sharply when source text has OCR errors or requires cross-field validation.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-21T12:54:18.512666+00:00— report_created — created