Practice · Established · Beginner

System Prompt

The persistent instruction block that sets an assistant's role, rules and output conventions before any user message.

What System Prompt is

The system prompt is the product's personality and policy layer: who the assistant is, what it must never do, what format it returns, and how it should handle uncertainty.

How it works

It is sent with every request and consumes context on each call. Teams keep it version-controlled, test it against regression suites, and avoid embedding secrets in it because it can often be extracted.

Why it matters

Most behaviour complaints in a deployed assistant are fixed here rather than by changing the model.

Common uses

→Assistant persona and tone
→Safety and refusal rules
→Output format enforcement
→Tool usage policy

Strengths

✓Central control point
✓Instant to change

Watch for

✓Extractable by determined users
✓Adds token cost per request

Continue exploring

Prompt Injection AI Guardrails Prompt Engineering