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Overview

The Validator step acts as a quality gate in your workflow. It takes the output from previous steps and checks it against validation rules you describe in natural language. The AI evaluates each rule and returns a boolean valid result plus an array of specific error messages for any rules that failed. This is useful when you need to:
  • Verify required fields are present before writing to a database
  • Check that API response data meets expected formats or ranges
  • Enforce business rules (e.g. “royalty rate must be between 0 and 1”)
  • Catch bad data early before it flows to downstream steps

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How It Works

At runtime, the Validator receives the full execution context as input. Your prompt defines the rules to check. The AI returns a structured result with valid (true/false) and errors (an array of human-readable error strings). When valid is false, you can use branches to route the workflow to an error-handling path.
Prompt:
Output when valid:
Output when invalid:

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Configuration

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Writing Good Prompts

  • List rules explicitly — each rule on its own line makes it easier for the AI to evaluate and report individually
  • Include expected types and ranges — “must be a number between 0 and 100” is better than “must be reasonable”
  • Be specific about what counts as failure — e.g. “empty strings and null values should fail the non-empty check”

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Using Libraries

The prompt editor has built-in library integration. Click Library above the editor to load a saved prompt, or click Save to store the current prompt as a reusable library item. This is useful when the same validation rules apply across multiple automations.

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Output

The Validator returns only valid and errors. A failing rule is a normal result (valid: false) — not a step error. If the underlying AI call itself fails, the step throws and is marked errored in the run logs; there are no error or error_message output fields.
Combine with branches to create conditional paths: add a branch on output.valid equals false to route to error handling, and let the default connector continue the happy path.