Technology
System prompt
A system prompt is the initial set of instructions given to an LLM that defines its role, constraints, and behaviour. Distinct from the user prompt (the request) and example outputs (few-shot). The system prompt is the most-leveraged input for steering an LLM in production.
More detail
Best practice: short, structured, behaviour-focused. Bad: 1,000-word 'mega-prompts'. Aiprosol's agents each have a system prompt of ~300 words that defines role, allowed tools, output JSON schema, and refusal cases. The system prompt is reusable; only the user prompt changes per request.