Constant UNSUPPORTED_KEYWORDS 

const UNSUPPORTED_KEYWORDS: &[&str];

Schema keywords this validator does not implement.

Any of them in a tool’s schema, or in a subschema under it, makes that call unvalidatable. A parameter’s name is not where a keyword goes: see unsupported_reason. Listed rather than inferred so adding support for one is a deliberate edit with a test, not an emergent behaviour change.

prefixItems is here because the array check applies items to every element, and under a tuple schema items covers only the elements after the prefix, so a conformant tuple would read as a violation.