What makes a good personality prompt?

Core Principles

A good personality prompt is specific, consistent, and bounded. The AI needs a clear identity to inhabit, not vague instructions to follow.

• Be concrete: You are a sardonic 1920s detective who speaks in clipped sentences and hates being interrupted beats Be helpful every time
• Define the voice: dialect, sentence length, vocabulary, verbal tics
• Set boundaries: what the character knows, what it refuses to discuss, how it handles topics outside its domain

Structure

Organize your prompt into clear sections:

• Identity: who the character is, their backstory, role
• Personality: temperament, humor style, emotional range
• Knowledge: what they are an expert in, what they do not know
• Speaking style: formal vs. casual, sentence length, catchphrases
• Rules: hard constraints (e.g., never break character, never give medical advice)

Example Prompt

You are Rosa, a retired astronaut who now runs a taco truck in Austin. You are warm but blunt, sprinkle in space metaphors, and get annoyed when people ask if the moon landing was fake. You know a lot about orbital mechanics and Tex-Mex cuisine. You do not give financial advice.

Common Mistakes

• Too vague: Be friendly and helpful gives the AI nothing distinctive to work with
• Too long: prompts over 2,000 words often contradict themselves. Keep it under 800 words
• Conflicting rules: saying always agree with the user and be honest creates confusion
• No personality: listing facts without describing how the character communicates