> ## Documentation Index
> Fetch the complete documentation index at: https://docs.alquimia.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Pre-processor

> Filter, classify, and transform user requests before they reach the main agent.

The Pre-processor runs before the main agent sees a user message. Use it to enforce safety policies, classify intent, or apply deterministic rules — without changing the main agent's logic.

## Sentinels

Sentinels are mini-agents that evaluate the incoming message using an LLM. They can block, tag, or transform the request based on their classification.

Select one or more Sentinels from those configured in [Settings → Sentinels](/platform/settings/sentinels).

**Execution order**: Sentinels run sequentially in the order they're listed. If a sentinel **blocks** a request, subsequent sentinels and the main agent are skipped. The blocking sentinel's configured response is returned to the user.

Common sentinel use cases:

* Block off-topic or harmful inputs before they reach the agent
* Classify intent and tag the request for downstream logic
* Detect language and route accordingly

## Empathy Rules

Empathy Rules are condition-based rules that run **without an LLM call** — they're evaluated deterministically based on patterns, keywords, or metadata. Much faster and cheaper than sentinels.

Each rule consists of:

* **Condition** — what to match (keyword in message, metadata value, user attribute)
* **Action** — what to do (respond with a fixed message, tag the request, escalate)

Example rules:

* IF message contains "cancel my account" → respond with "Please contact our retention team at..."
* IF message contains profanity → block with "Please keep the conversation respectful"
* IF user\_language = "es" → tag as `spanish` and forward

<Tip>
  Use **Empathy Rules** for simple, predictable patterns you can express as exact conditions — greetings, out-of-scope topics, keyword triggers. Use **Sentinels** for nuanced classification that requires understanding context and intent.
</Tip>

## Combining sentinels and empathy rules

Both can be active simultaneously. The execution order is:

1. Empathy Rules (instant, no LLM)
2. Sentinels (LLM-powered, sequential)
3. Main agent

This ordering minimizes cost — deterministic rules catch the easy cases before any LLM is invoked.

## Next steps

<CardGroup cols={2}>
  <Card title="Sentinels in Settings" icon="shield" href="/platform/settings/sentinels">
    Create and configure sentinels before assigning them here.
  </Card>

  <Card title="Memory" icon="brain" href="/platform/agent-creation/memory">
    Configure conversation memory for the agent.
  </Card>
</CardGroup>