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Signals let you ask a yes/no question about incoming request logs and automatically label matching production traffic true or false. Each evaluation includes reasoning and a quote from the request so you can review why PromptLayer classified it that way. Signals enrich request logs. Return to Configure Request Logging for the other enrichment options. For example, you can ask whether the assistant answered in the user’s language, whether a required disclaimer was included, or whether the model stayed on topic.
Request log with Signal labels showing true or false results

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Create a Signal

  1. Open Signals in the PromptLayer sidebar.
  2. Select New signal.
  3. Enter a name and write your yes/no question in the signal statement field.
  4. Add one or more hooks to define where the signal runs and how often it is sampled.
  5. Save the signal. When you are ready for production evaluation, turn Enabled on.
Signals list showing signal cards with processed counts and true or false percentages
The Signals list shows each signal’s question, scope, and running totals for processed requests and true/false distribution.

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Scope with hooks

Each hook controls which request logs a signal evaluates and at what rate. Each hook has its own sample rate (default 50%). PromptLayer evaluates only the sampled share of matching traffic, which helps control cost on high-volume prompts. A signal can have multiple hooks. Use this when the same question should apply to different prompts, labels, or sampling rates.
Signal editor with statement, scope hooks, sampling rate, and test panel

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Test before enabling

Before you enable a signal in production, test it on real request logs:
  1. In the Test on selected requests panel, add up to 20 request logs from history or from your current scope.
  2. Run Try signal on individual logs or Test all across the set.
  3. Review the true/false result, reasoning, and citation for each log.
Testing does not change production behavior. Use it to refine your signal statement and confirm the labels match your expectations.

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Use results in Request Logs

When a signal is enabled, evaluated requests show true or false labels in the Request Logs table and in request details. Select a label to filter the table to matching results. See Search to filter request logs by signal results from the search bar.

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Signals, tags, and scores

Signals, tags, and scores all help you organize and review request logs, but they work differently: Use tags for manual categorization at log time. Use scores when you need a numeric rating. Use Signals when you want PromptLayer to continuously evaluate production requests against a yes/no question.