Evidence and limits
Finding: Accuracy-only evaluation can reward complex, expensive agents, obscure the source of gains, and encourage benchmark overfitting. Downstream users and model developers also need different evaluation evidence.
Impact: Strengthen joint cost-and-outcome evaluation, holdouts, and downstream-fit reporting.
Boundary: This is a methodological critique, not a field test of one collaboration workflow. Next: what minimum holdout and replay design prevents Breadcrumbs patterns from overfitting their own examples?
Flags: preprint; benchmark and cost-definition dependence
Record State: Catalog review recorded; not a performance endorsement
What was reviewed: Structure and relevance screened; not a full evaluation