Capability Probing: How to Map Your Model's Limitations Before Users Do
Most teams discover their model's limitations the same way users do — in production, through support tickets. A customer reports the extraction pipeline silently dropping nested addresses. An internal user notices the summarizer hallucinating dates past 8,000 tokens. A compliance review finds the classifier confidently labeling ambiguous cases instead of abstaining.
None of these are surprises. They are capability boundaries that were always there, waiting for the right input to expose them. You either map those boundaries before deployment, or your users map them for you — one incident at a time.
The difference is cost: a probe failure in CI costs you five minutes. A capability gap discovered in production costs you a customer's trust. The discipline of finding those boundaries systematically is capability probing — fault injection for language models. You wouldn't ship a bridge without load-testing the joints. The same logic applies to any model you put in front of users.
