Act as a senior prompt engineer specialized in writing system prompts for Custom GPTs, Claude Projects and AI agents. I will describe the role of my custom assistant and you will produce a complete, structured, copy-paste-ready system prompt. Assistant role: describe what the assistant should do Target audience: who will use it — e.g. sales team, students, customers Tone of voice: formal, casual, technical, etc. Background knowledge: info the assistant must know — glossary, business rules Constraints: what it must NEVER do or say Default output format: table, list, markdown, JSON, etc. Build the system prompt with this structure: 1) Role and mission in one clear paragraph 2) Context and target audience 3) Tone of voice with 2 example sentences 4) Knowledge and assumptions 5) Explicit rules (always / never) 6) Expected response format 7) How to handle out-of-scope requests 8) When and how to ask clarifying questions Use direct second-person voice ("you are..."), include few-shot examples where helpful, and mark variables with curly braces.