Guardrail
A guardrail is a check or control applied around an AI system’s inputs, outputs, or actions. It can block, transform, or route behavior according to a rule or a model-based assessment.
[LangChain]In practice · hypothetical example
A support assistant masks email addresses in a draft before displaying it in a shared review queue.
[LangChain]A little deeper
Rule-based checks are predictable but can miss nuances. Model-based checks can handle more context but can also make errors. The term describes a family of controls, not a guarantee. [LangChain]
A common mix-up
A guardrail makes any agent action safe.
A check covers the cases it detects; other controls and evaluation remain necessary. [LangChain]
A filter masks an email address before display. What is its role?
Sources & editorial notes
Evidence: supported. Primary-source support for this scoped entry; publication approved by the project owner.
- Guardrails ↗ (opens in new tab)LangChain · Publication date unknown
Relevant section: Deterministic guardrails; Model-based guardrails
Last editorial review: 2026-09-13 by project-owner.
First observed in this corpus: Unknown.
Revision history
Revision 2 · Created 2026-09-13 · Updated 2026-09-13
Project owner approved the current content for publication. Existing evidence scope and limitations remain applicable.