I Replaced 3 Hours of Prompt Engineering with a 50ms Free API Call

The secret? Stop treating prompts like strings. Start treating them like compiled code. Last month I was building a customer agent for a client. Standard stuff: Claude-powered, MCP-connected, deployed on their Slack workspace. The agent took me 2 hours to build. The prompt took me 3 days. Every time I thought I had it right, the agent would: Lose its persona after 4-5 messages Forget constraints I explicitly defined Respond generically when it should have escalated Behave differently on Slack vs.