An unchanged retry repeats the same task specification and therefore commonly reproduces the same invalid interpretation. The validator has generated precise corrective information— quantity requires a float, but the model returned the range string 2 to 3 . Supplying that error in a follow-up turn converts a generic retry into an iterative repair operation.

Anthropic identifies iterative refinement as a method for detecting and correcting inconsistencies by feeding an earlier output back into a subsequent request with targeted instructions. ( https://docs.anthropic.com/en/docs/test-and-evaluate/strengthen-guardrails/reduce-hallucinations ) Option A applies that pattern directly. Claude receives the invalid output, the exact Pydantic error, and an instruction to return a schema-compliant correction. The application should cap retries, retain the original source, and escalate cases that cannot be represented without information loss.

Option B does not guarantee correct formatting; lower temperature may make the same wrong output more repeatable. Option C can be valuable for systematic OCR or source-format problems, but it is unnecessarily broad when the immediate failure is already described by the validator. Option D increases cost and complexity without first using the actionable feedback available from the existing validation layer.

For supported models, native Structured Outputs should also be considered because they guarantee schema-conformant JSON and can prevent many Pydantic shape failures before they occur. ( https://platform.claude.com/docs/en/build-with-claude/structured-outputs )

Official references/topics: Iterative Refinement; Validation-Error Feedback; Bounded Retry Loops; Structured Outputs.