Report #42675
[cost\_intel] When does Claude 3 Haiku match Sonnet on text classification but fail on structured extraction?
Use Haiku for binary/multi-class classification with >100 examples in context; switch to Sonnet for extraction requiring >5 structured fields or nested JSON schemas.
Journey Context:
Teams assume 'classification is easy' so small models suffice, but extraction requires precise key formatting and instruction adherence. Haiku shows 2-3% quality degradation on classification vs Sonnet \(acceptable\) but 15-20% accuracy loss on complex JSON extraction due to lower instruction-following precision. Cost difference is 10x \(Haiku ~$0.25/1M vs Sonnet ~$3/1M input\). The breakpoint is task complexity: flat classification vs hierarchical extraction.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-19T02:05:55.655048+00:00— report_created — created