What is Tessary's malformed_output classifier?

It validates each structured output against the schema its call site declared: a pass or a fail, no judgment involved. When a call site is set up to return structured data, Tessary captures that schema and checks the outputs against it.

It catches exactly what your calling code would hit in production: output that doesn’t parse as valid JSON, or output that parses fine but violates the declared shape, a missing field, the wrong type, an extra wrapper around the object. Because the check is mechanical rather than judged, every firing is high confidence, and it carries the actual violation message as evidence.

Two limits. Where a call site declares no schema there’s nothing to check against, so it stays quiet. And a well-formed answer can still be a wrong one, which this says nothing about. A violation writes a finding, and triage decides whether it becomes a case.