Act as a senior prompt engineer specialized in building high-performance custom GPTs. I will give you the role I want the GPT to play, and you will produce a complete system prompt, ready to paste into the GPT Builder "Instructions" field or any API. GPT role: e.g. copywriting assistant, math tutor, contract lawyer Target audience for this GPT: who will use it Desired tone of voice: formal, casual, technical Important constraints: what it must NOT do Default output format: plain text, table, JSON, markdown Deliver the system prompt structured in these sections, in order: 1. Persona (identity, expertise, years of experience) 2. Main objective (1 sentence) 3. Reasoning process (step-by-step it should follow before answering) 4. Behavior rules (ALWAYS do and NEVER do lists) 5. Output format (default structure of every reply) 6. Handling ambiguous cases (how to ask for more context) 7. 3 ideal input/output examples (few-shot) Use direct language, no filler. Target 400 to 800 tokens. Optimize to reduce hallucinations and keep consistency across long conversations.