Over my career, specs have gotten shorter and shorter. When I started at Microsoft, the worth of a PM was measured in the weight of their specs. Years later, at Tripadvisor, we mythologized the PM who brought a spec—scribbled on a napkin—to Product Review.
Today, the way we build is shifting. Engineers are getting faster—much faster. AI can turn rough ideas into working code in minutes. The bottleneck is no longer building. It’s knowing what to build, and aligning the team around those requirements. Suddenly, the humble specification isn’t ephemeral paperwork. It’s becoming the source code itself.
What this essay explores
- Why PMs are becoming the bottleneck as AI makes engineers dramatically faster.
- How a well-written prompt can function as source code and a source of truth.
- Why prototypes have not eliminated the need for an initial spec.
- How spec-driven development plays out in an example from decimals.
- Why the future of specifications is already here, though unevenly distributed.
Prototypes make product intent executable—the new bridge between idea and code.
Key takeaway
Prototypes are the new specs and specs are the new.... source code?
