One Agent Run Becomes a Corpus Test Suite

Instead of classifying every document with a language model, researchers used a tool-using agent once as a corpus debugger. Three runs over the 26.5-million-document Slovak slice of FineWeb2 cost $2.21 to $2.84 each and produced seven findings across four phenomena. Native-speaker review supported six. The largest was a machine-generated content farm containing 1,408,437 documents, or 5.32 percent of the corpus. The compiled tests then scanned the full slice in 0.7 seconds without a GPU. A static sampling baseline validated more selectors at lower cost, so the agent's value was in prevalence estimates, explanations and reusable tests rather than unqualified superiority.