System Prompt Architect
One-off prompts are for one-off tasks. When you want an assistant that behaves the same way every single conversation — your support agent, your editor, your tutor — you write a system prompt once and reuse it forever. Build yours here, section by section.
Advanced · builds as you type
Design your assistant's constitution
A system prompt is the standing instruction set an assistant reads before every conversation. Fill in what applies — empty sections are left out.
“You are …” — the persona every reply speaks from.
Facts it should always know: your business, product, policies, project.
Who it talks to and how it should sound.
Standing do’s. Each line becomes a bullet.
The default shape of every answer.
Hard guardrails. Each line becomes a bullet.
+ Few-shot example (the single strongest tone control)
Your system prompt · updates live
You are [identity]. # Standing knowledge [what it should always know] # Audience & tone [who it talks to, how it sounds] # Rules - [rule] # Output format [default shape of every answer] # Never - [hard guardrail]
Paste it into Claude Projects (project instructions), ChatGPT custom instructions / GPTs, or Gemini Gems — the same block works everywhere.
Want the “why” behind this tool?
Tools build the reflex; the guide builds the understanding. They're better together.