A lead replies "sure, let's chat" at 2 AM. By the time you see it at 9, they've cooled off. So I built a reply agent on Make.com that handles it within a minute, 24/7: - Reads the reply and classifies intent (meeting request, time picked, question, not interested, OOO) - Checks my Cal.com calendar and offers the 2-3 fastest open slots - Books the call when the lead picks a time - Replies through Smartlead in the same thread - Logs every decision to Supabase Stack: Make.com AI Agent + Smartlead + Cal.com + Supabase. The biggest lesson: lock down everything the agent doesn't need to touch. URL, method, headers and query params stay fixed in each HTTP module, and the agent only fills the request body from a strict prompt. Every time I gave it more control, something broke. The guide covers the full setup, the system prompt, the tool prompts I used, and the 8 errors I hit with the fix for each. Get it full details in courses. Drop a comment if you're building something similar or get stuck on a step. Happy to help.