The plain-English version
An explicit rule for when a system should report insufficient evidence, ask for needed information, or decline to assign a result.
Why it matters
It gives uncertainty an intentional user-visible outcome.
Let’s make it click
A document assistant returns “No supported deadline found” when none of the supplied passages gives a date.
Vibe Bro’s heads-up
Do not turn a model-generated confidence percentage into a calibrated probability without evaluating that claim.
You might also hear
- unknown outcome
- insufficient evidence
- uncertainty handling
The docs behind it
Research sources reviewed .
Editorial review · October 28, 2026
Supported: Anthropic recommends permitting uncertainty and grounded claims. The missing-evidence rule is original guidance; it appropriately does not treat an uncalibrated confidence percentage as probability.