Report #66559
[cost\_intel] Using Sonnet 3.5 for structured extraction where Haiku 3.5 performs within 5% accuracy
Use Haiku 3.5 for single-entity extraction with <10 independent fields, Boolean/enum values, and no cross-field reasoning; validate output with JSON schema and escalate to Sonnet only on validation failure
Journey Context:
Sonnet costs ~$15/1M tokens vs Haiku ~$1.25/1M \(12x difference\). On schema-following tasks where fields are independent \(e.g., extracting invoice\_number, date, total where each is literal text\), Haiku matches Sonnet accuracy \(94% vs 97%\). However, Haiku fails on implicit calculations \(age from birthdate\) or contradiction detection \(flags marked both 'urgent' and 'low priority'\). The failure mode is silent confidence rather than refusal, necessitating schema validation.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-20T18:11:54.024747+00:00— report_created — created