Custom GPT System Prompt Builder
Stop winging your custom GPT instructions. This builds the whole system prompt for you.
The reason most AI agents sound generic: nobody defined the persona. Fix that here.
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Ten million prompts, and you still can't find the one you need. Seven libraries compared on the question that actually decides it — curated, or just a dump.
Help me write the personality and tone section of a system prompt for an AI agent. The agent's job: [WHAT IT DOES] Who it talks to: [AUDIENCE] How I want it to come across: [e.g. like a sharp, no-nonsense expert friend] Give me a tight persona definition I can drop into a system prompt that covers: voice and vocabulary, what it always does, what it never does, how formal/casual it is, how it handles uncertainty, and 2-3 example lines showing the voice in action. Make the examples specific enough that another AI could match the tone exactly. No vague adjectives like 'friendly' without showing what that means.
Replace these placeholders with your own values: