Idea Stress-Test: Four Prompts Before You Spend a Dollar
Run this four-prompt sequence and put any business idea through a structured stress-test before you commit time or capital.
Free prompt pack · copy-paste ready · built by the BrainVaultAI team
Most founders validate by talking to people who tell them what they want to hear, or by Googling TAM numbers that are always in the billions. Neither tells you if the idea will actually work. This four-prompt sequence stress-tests an idea from four angles that most people skip: what the market data actually says (not the upside case), why the target customer hasn't solved this already, what makes this defensible, and whether the unit economics close before you run out of runway. Run all four before you write a line of code or spend a dollar on ads. The sequence takes 20 minutes. It will either kill bad ideas fast or give you a sharper pitch for the good ones. Do not modify the prompts to be softer. The value is in the adversarial framing. If Claude punches holes you can't answer, that's information.
Prompt 1: Market reality check
I'm evaluating a business idea. Do not help me validate it. Help me stress-test it. Idea: [describe in 2-3 sentences, what it is, who it's for, what they pay] Tell me:
1. What does existing market data suggest about this category, including signals that the market is harder or smaller than it looks?
2. Who has tried this before and failed? What specifically killed them?
3. What macro or behavioral trend would have to be true for this to work? Is that trend real or assumed?
4. What's the most honest TAM for the specific segment I'm targeting, not the category, the actual segment? Be specific. Cite categories, analogies, and market patterns. Do not give me the upside case unless I ask.
Prompt 2: Customer psychology stress-test
Continuing the stress-test of this idea: [paste idea description] Focus on the target customer: [describe who they are, job, context, pain level] Tell me:
1. What is the customer doing RIGHT NOW to solve this problem without my product?
2. Why haven't they already paid for a better solution, what's the real reason (inertia, budget, awareness, doesn't actually hurt that much)?
3. What would have to be true about their current situation for them to switch to something new?
4. What's the buying trigger, the specific moment when they decide to act?
5. Who in their life or organization would push back on them buying this? Do not assume the problem is urgent just because I think it is.
Prompt 3: Competitive moat analysis
Continuing the stress-test. Same idea: [paste idea description] Tell me:
1. If this works, what stops a well-funded competitor from copying it in 18 months?
2. What would a scrappy solo founder build to undercut me on price in 12 months?
3. What would a large incumbent do to absorb this as a feature?
4. What is the one thing I could build or establish in year one that makes me harder to displace over time? Is that actually achievable with my constraints?
5. Rate the defensibility of this idea: low / medium / high, and give me the one-sentence reason. Don't tell me network effects or data moats are defensible without explaining specifically how I'd build them.
Prompt 4: Unit economics reality check
Final stress-test prompt. Same idea: [paste idea description] Price point I'm planning: [$/month or one-time]
How I plan to acquire customers: [channel, organic, paid, outbound, etc.]
My rough cost to deliver: [what it costs me to serve one customer per month] Tell me:
1. What does my CAC likely need to be for this channel to work, based on industry benchmarks?
2. What LTV do I need to make that CAC acceptable, and does my price point get me there?
3. What churn rate would kill this business even if everything else worked?
4. How many customers do I need before the unit economics are self-sustaining?
5. What's the single biggest number I'm probably wrong about in my assumptions? Give me a verdict: viable, marginal, or broken, and the one thing that would change the verdict.
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