I've spent the last few months building and selling prompt packs to freelancers and agencies, and here's the uncomfortable truth: most prompt packs floating around are written for demos, not delivery.

A prompt that makes a great screenshot rarely survives a real client brief with actual constraints — brand voice, industry compliance, weird formatting requirements, a client who hates em-dashes.

The packs that actually get reused are the ones built backwards from a deliverable: start with the exact output an agency needs to hand off (a sales page, an email sequence, an ad set), then reverse-engineer the prompt chain to get there reliably, not just once.

A few things that changed how I write prompts after enough client feedback:

• Constrain the output format explicitly. "Write 3 variations, each under 150 words, no headers" beats "write some options."

• Bake in the revision loop. The best prompts include a follow-up instruction for tightening/expanding, so you're not starting from scratch when a client says "shorter."

• Test on ugly briefs, not clean ones. If a prompt only works with a perfect brief, it's a demo, not a tool.

Built a marketplace around this idea — packs tested on real client work, not just vibes. Happy to share what's worked if anyone's building their own prompt library too.