
October 20, 2026 · 15 min read
How to Validate a Startup Idea Before You Build
A working prototype used to be evidence. Now a coding agent will build a convincing version of any idea you describe, including the bad ones, which means "we shipped it" has stopped filtering anything. The only expensive step left is deciding whether the thing deserves to exist. Garry Tan, president and CEO of Y Combinator, built that decision into a Claude Code skill: six forcing questions, modeled on YC partner office hours, that run before the agent writes a line. Inside: what each question is actually testing and the red flag that means you have not answered it, which questions matter at your stage, the gate working on a real idea where it separated pain from consequence and reframed the idea into an expansion Tan guessed might be worth ten times more, why a gate that never kills anything is not a gate, and the one input no agent can supply for you.
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