From Slash Commands to Real Skill Engineering: 3 Lessons I Learned the Hard Way

I wrote an email-processing Skill with 8 detailed rules. Claude followed every one of them like an obedient but soulless intern - the output was correct but completely useless. Then I deleted all 8 rules and replaced them with two sentences: "Which emails need my action, and which do I just need to know about?" The result was 3x better. Claude started organizing information by urgency, merging redundant emails, and even flagging ones I could safely ignore. That experience taught me something: writing instructions ≠ Skill engineering. There are three cognitive layers between the two.