# Guardrails URL: /reference/blocks/system-guardrails Type: reference Description: Validate outputs, detect hallucinations/PII Keywords: guardrails, system/guardrails, system, block, workflow builder `system/guardrails` — Validate outputs, detect hallucinations/PII. Where it appears [#where-it-appears] The **Guardrails** block lives in the **Logic & control** group of the Workflow Builder. Fields [#fields] | Field | Type | Required | Default | Description | | --------- | ---- | -------- | ------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `payload` | code | No | — | JSON payload the guardrails run against to detect hallucinations and PII. Use \ to pass in upstream content (e.g. a generated draft). Leave empty to check the default upstream output. | Inputs and outputs [#inputs-and-outputs] Inputs are the configurable fields above. The block produces these outputs: **Outputs** Reference an output downstream with ``. | Name | Type | Description | | ----------------- | ------- | ------------------------- | | `success` | boolean | Whether guardrails passed | | `policy` | json | Policy applied | | `redactedPayload` | json | Redacted payload | | `warnings` | array | Warnings array | | `error` | string | Error if failed | Limits and failure modes [#limits-and-failure-modes] * On failure the `error` output is populated; downstream blocks that reference other outputs may not receive values. Related [#related] * [All workflow blocks](/reference/blocks) * [Workflow Builder overview](/workflow-builder-overview)