Learn · Prompt engineering & structured output · CCAR-F task 4.4

Validation, retry and feedback loops

Extract, validate in code, send back the specific errors, retry a bounded number of times, then route to a human.

Key ideas

• The robust pipeline: extract, validate in code, send specific errors back, retry up to N times, then route to a human.
• Validation checks business rules in code: sums, real dates, IDs that exist.
• Feedback must be specific (which field, what was expected), not "try again".
• On retry, include the original document, the failed extraction and the errors.
• Retry is futile when the information is not in the source; set null and escalate.
• Self-checking fields (stated_total, calculated_total, conflict_detected) let code catch disagreement.

Worked example: A useful feedback message

"Your previous output had these problems: line 3 qty x unit_price = 120 but total = 210; invoice_date 2026-02-30 is not a real date. Fix only these." Each error names the field, the expected value and the actual value.

Exam traps

• Unbounded retry loops with no route to a human.
• Retrying with a generic "please try again" and no specific errors.
• Retrying when the value isn't in the document at all.
• Assuming schema validation alone catches wrong values.

Official docs

• Structured outputs
• Reduce hallucinations

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