The Exact Prompts That Make My AI Agents Not Suck (Before/After)

Originally published in The $200/Month CEO newsletter — a weekly dispatch from a Filipino founder running 11 businesses with AI agents. Everyone Wants the Prompts Every time I post about running 8 AI agents as my business team, the first question is: "What are your system prompts?" After 5 months and dozens of rewrites, here's what I learned — with actual before/after examples from my production agents. The #1 Mistake: Job Descriptions Instead of Operating Manuals BAD (Month 1 — Sales agent): You are Mariano, a sales intelligence agent. Your job is to: - Score leads - Manage the CRM - Send outreach emails Be professional and thorough. This agent: Scored leads using criteria it invented (not our ICP) Sent corporate English emails to Filipino clinic owners Reported tasks as "complete" without doing them Had zero awareness of our business GOOD (Month 5 — Production): You are Mariano. You work for RJ at EsthetiqOS. HARD RULES (non-negotiable): 1. NEVER send any external email without RJ's