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A Sentinel is a mini-agent that runs before the main agent processes a user message. It intercepts the input, applies a classification or safety check, and can block, transform, or tag the request.

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Use cases

  • Content moderation — block harmful or off-topic inputs
  • Intent classification — tag the request type for downstream routing
  • PII detection — flag or redact personal information
  • Language detection — route to a language-specific agent
  • Topic enforcement — ensure users stay within the agent’s defined scope

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Sentinel vs Safeguard Model

These are two distinct concepts:
TermWhat it is
Safeguard ModelThe LLM configuration used by the sentinel — its “brain”
SentinelThe complete pre-processor: a safeguard model + system prompt + conditions
Think of the safeguard model as the engine and the sentinel as the car.

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Adding a sentinel

Click Add Sentinel: Profile section — defines what the sentinel does:
  • System Prompt — instructions for the sentinel’s LLM. E.g.: “You are a content moderator. Classify the following user input as safe or unsafe. Return only the classification label.”
Config section — which model powers the sentinel:
  • References a Safeguard Model registered in Settings
Conditions section — what happens based on the sentinel’s output: The visual condition builder lets you define rules like:
  • IF sentinel returns unsafe → block the request with a fixed message
  • IF sentinel returns billing → tag the request and allow through
  • IF sentinel returns escalate → forward to a human handoff flow
Sentinels run synchronously before the main agent. Every user message waits for the sentinel to complete. Use small, fast models (e.g., 7B or smaller) for classification tasks to keep latency low.

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Using sentinels in agents

Once a sentinel is created here, it becomes available under Pre-processor during agent creation. Multiple sentinels can be chained — they run in order, and if one blocks the request, subsequent sentinels and the main agent are skipped. See Pre-processor for how to assign sentinels to agents.

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Next steps

Pre-processor

Add sentinels and empathy rules to an agent.