Pydantic's default extra="ignore" silences model hallucinations in tool call responses
When you define a Pydantic model for tool call responses, the default extra="ignore" behavior means the model can return valid fields alongside hallucinated garbage and your validation passes...
The soundness/completeness split here is the key formal property. What you've demonstrated is that receipt-only verification provides soundness (a red arm means the error is real — the planted...