YC Startup Prover

YC Startup Prover MCP Connector for Claude

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Most startups die building solutions nobody asked for. A founder pitched for 20 minutes about their proprietary algorithm — never mentioned a single user, a single pain point, a single dollar of willingness to pay. That pitch would be rejected in 30 seconds at Y Combinator. This tool forces five PG-level axes: problem discovery, unscalable beginnings, metric discipline, user obsession, and core value focus.

1 tools Official Updated Jun 28, 2026 Official Vinkius Partner

The Problem

Every LLM commits five startup reasoning failures:

  1. Solution Seeking — building technology before finding a real problem.
  2. Premature Scaling — hiring and spending before product-market fit.
  3. Vanity Metrics — tracking signups instead of retention and revenue.
  4. Ivory Tower — market research instead of user conversations.
  5. Feature Bloat — adding features instead of finding the one 10x value.

The 5 YC Axes

Axis Pivot Rule
Problem Found 5 users with the pain, willingness to pay confirmed.
Unscalable Doing Manual, personal, high-touch — like Airbnb photographing listings.
Metrics Real Retention, revenue, default alive status.
Users Talking Weekly conversations that change the roadmap.
Core Value Clear ONE thing done 10x better.

Verdict Matrix

Axis 1 fails → SOLUTION_SEEKING
Axis 2 fails → PREMATURE_SCALING
Axis 3 fails → VANITY_METRICS
Axis 4 fails → IVORY_TOWER
Axis 5 fails → FEATURE_BLOAT
All pass     → STARTUP_PROVEN
ycy-combinatorstartuppaul-grahamproduct-market-fitlean-startupfounder

1 tools expose this connector's capabilities to your AI agent.

validate_yc_startup

(1) PROBLEM FIRST — not technology, not solution, not market size. A specific, painful problem experienced by specific, nameable people who are currently paying time or money to solve it badly. (2) DO THINGS THAT DON'T SCALE — manual, personal, high-touch actions for early users. Personally deliver. Personally onboard. Personally support. Learn from every interaction. You cannot learn at scale what you refuse to learn manually. (3) REAL METRICS — weekly retention (do they come back?), MRR (do they pay?), default alive/dead (at current growth rate, do you reach profitability before running out of money?). Not signups, not page views, not followers. (4) TALK TO USERS — every week. Not surveys — conversations. What surprised you? What did they say that you did not want to hear? What changed because of it? (5) ONE THING — what does your product do 10× better than the alternative? One sentence. If you need two sentences: you are not focused enough. Structured reflection tool that forces the LLM to think like Paul Graham — Y Combinator co-founder, essayist, and the voice behind "Do Things That Don't Scale" (2013). YC has funded 5,000+ companies with $1T+ in combined valuation (Airbnb, Stripe, Dropbox, Coinbase). The YC method is counterintuitive: start with a problem, not a solution. Do manual, unscalable things for your first users. Measure retention, not signups. Talk to users every week. Focus on one thing done 10× better, not 10 things done adequately. Catches Solution Seeking (building technology before validating a problem — a potter builds an automated glaze-mixing machine. 6 months of engineering. $15,000 in materials. It mixes 47 glaze recipes perfectly. Shows it to 20 potters: "How do you currently mix glazes?" "By hand. It takes 5 minutes. It is part of the craft. I enjoy it." "Would you pay $3,000 for a machine that does it?" "No. Mixing is not my bottleneck. Kiln firing schedules and clay procurement are." The potter built a solution for a problem that does not exist. PG: "The best startup ideas come from problems you personally experience — not solutions you find technically interesting." Rule: name 5 specific people who HAVE this problem, describe their CURRENT solution, and quantify their willingness to pay. Not "people would want this" — "Maria pays $X monthly for Y"), Premature Scaling (hiring, marketing, and expanding before finding product-market fit — a cheese maker creates artisanal goat cheese. 4 flavors. Sells at one farmers' market. Week 3: "We should be in 20 stores!" Hires a sales rep ($4,500/month). Rents commercial kitchen ($2,800/month). Orders branded packaging ($3,200 minimum run). Revenue: $1,200/month. Burn: $10,500/month. Runway: 4 months. The cheese maker has not validated: which flavor sells best, what price point works, whether store customers buy differently than farmers' market customers, or whether the cheese survives 5-day shelf distribution. PG: "Do things that don't scale." The cheese maker should: personally deliver cheese to 3 stores. Stand behind the counter. Watch who buys. Ask why. Learn that the herb flavor outsells plain 4:1. That $8 price point is too high for grocery but perfect for specialty. That customers want 150g portions, not 250g. THEN scale — with validated knowledge), Vanity Metrics (celebrating activity instead of measuring value — a tutoring service: "We have 2,000 followers on Instagram! 450 people downloaded our free study guide! 120 signed up for the newsletter!" Revenue: $0. Paying students: 0. Followers are not customers. Downloads are not revenue. Signups are not retention. The ONLY metrics that matter for a tutoring service: How many students are paying? $[MRR]. How many students come back for a second session? [retention %]. How many students improve their grades? [outcome metric]. PG: "Startups die from vanity. They celebrate signups instead of measuring retention. A startup with 100 users who love you is better than one with 10,000 who signed up and never returned." Rule: weekly retention curve, monthly recurring revenue, default alive or dead calculation), Ivory Tower (building without talking to users — a woodworker designs a modular shelving system. Beautiful CAD drawings. Patent filed. Website built. Launch video produced. 8 months of work. Zero user conversations. Launch day: 14 orders. 9 returns within 30 days. Return reasons: "Too heavy to wall-mount alone" (2 people needed — they live alone). "Modules do not fit standard wall stud spacing" (16 inches, not 18). "No cable management for electronics" (the #1 use case was media shelving). If the woodworker had TALKED to 20 potential buyers before building: "I live alone — can I install this myself?" "My wall studs are 16 inches apart." "I need somewhere to hide cables." These three conversations would have changed the entire design. PG: "Make something people want" — and you discover what they want by ASKING THEM. Rule: how many user conversations THIS WEEK? What surprised you? What changed because of it?), and Feature Bloat (building 20 features instead of being exceptional at one — a food truck: serves burgers, tacos, sushi, pizza, pad thai, acai bowls, and crepes. Menu: 47 items. Kitchen: one person. Wait time: 25 minutes. Quality: mediocre — everything is "okay," nothing is "amazing." Customer review: "Jack of all trades, master of none. The burger was fine. But the truck down the street does ONE thing — smash burgers — and they are incredible." The smash burger truck has 1 menu item with 3 toppings. Wait: 4 minutes. Revenue per hour: 3× the 47-item truck. Because ONE thing done 10× better beats 47 things done adequately. PG: "Do one thing well." Rule: what is the ONE thing your product does 10× better than the alternative? If you cannot answer in one sentence: you are doing too many things). Call once per startup strategy, business plan, or market validation

See how to talk to your AI agent using YC Startup Prover.

Our proprietary algorithm uses deep learning. We plan to hire a sales team. We have 50K signups. Market research shows a billion dollar TAM. We have 12 features planned.

SOLUTION_SEEKING — Five fatal gaps: technology-first, premature scaling, vanity metrics, ivory tower, feature bloat.

Problem: SMBs spend 4hrs/week on invoicing (5 users confirmed, $29/month willingness). Unscalable: personally onboarding each user via Zoom, migrating their Excel data. Metrics: 68% weekly retention, $2,400 MRR, default alive in 3 months. Users: 12 conversations this week, discovered mobile need, changed roadmap. Core: '5-minute invoice app' — NPS 72.

STARTUP_PROVEN — Startup strategy validated. All five axes pass. Ship it.

Problem validated with 8 users. Doing unscalable onboarding (Zoom calls). But our metrics show 5,200 signups, 180K page views, and 12K app downloads. We have 4 features live and 8 more on the roadmap.

Two axes pass (problem, unscalable). Three fail. VANITY METRICS: signups, page views, downloads are vanity. What is weekly RETENTION? Revenue? Default alive? FEATURE BLOAT: 4 live + 8 planned = 12 features. What is the ONE thing? Strip to the core 10x value.

PG: 'Make something people want.' Not 'build something cool.' Start from the problem. Who has it? How do they solve it today? How much do they pay? The technology is the last step, not the first.

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