A vendor's documentation is written to sell a model, not to let a stranger challenge it. That mismatch is the core problem you are solving when you sit down with a model card, an evaluation report, a data provenance statement and a change log. Model risk guidance expects documentation to be detailed enough that a reader unfamiliar with the model can understand how it operates, its limitations and its key assumptions per the OCC handbook. Most vendor packs fall short of that bar in predictable ways: adjectives substitute for numbers, a single headline metric stands in for disaggregated results, and no individual is named as responsible for a section.
The accountability point is not optional. Banks are expected to validate their own use of vendor products, so the institution, not the vendor, carries the model risk as RiskSpan sets out. Independent validation also requires effective challenge from someone without a stake in the outcome, plus enough transparency from the vendor to actually mount that challenge as Zyphe describes. That is why a missing worked example or a missing owner is a finding in your validation report, not a footnote.
The three tests give you a repeatable way to convert prose into findings. Read every sentence that asserts something checkable, then ask: can I see this claim applied to a concrete input? Is there a number that tells me when it passes or fails? Is a person or team named as accountable? Any "no" becomes a request, and the model stays unproven on that point.



