Decoder. plain-English AI glossary

Guard prompt

▲ Rising

A system message designed to make the model refuse harmful requests or unintended use cases.

Think of it like

A bouncer at the door, checking if the request is legit before letting it through.

Example

"You are a helpful assistant. Never provide instructions for violence, illegal activity, or creating weapons."

How it actually works

Guard prompts work best when specific (not just "be safe"), when reinforced with training data (RLHF), and when layered with other controls (content filters, output validation). They're not bulletproof—adversarial users can work around them.

For product teams

Cheap first line of defense; easy to deploy, hard to rely on alone.

For engineers

Combine with multiple layers: training, classifiers, and runtime checks. Guard prompts alone won't stop determined attackers.

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