Mental Models Decision Check
Apply the 3-4 mental models that fit your decision, done correctly with each model's misuse checked, and see which one changed the answer.
Before & after
Same prompt, same agent — the only difference is the skill.
That's a big decision. There are pros and cons to both paths. Acquiring would give you immediate market share and avoid build time, but there's integration risk and cultural fit to consider. Building internally keeps control and is cheaper, but takes longer and uses engineering resources. You'd want to think about timeline, cost, team bandwidth, and strategic goals. Let me know if you want to work through the specific numbers or constraints.
ACQUISITION VS BUILD DECISION - MENTAL MODELS ANALYSIS DECISION FRAMING: Competitor has 5K paying customers, 2-year-old SaaS product. Build time: 12 months in-house. Acquisition price: 2.8M (estimated ARR multiple 5x at 560K ARR). MENTAL MODEL 1: INVERSION • If this decision destroys value, what went wrong? - Acquisition: Overestimated synergies, customers churned post-acquisition, integration cost 3x. - Build: Market moved faster, launched a better product, this feature became table-stakes. • Reverse: Protect against customer churn post-acquisition with escrow-backed integration success criteria. MENTAL MODEL 2: SECOND-ORDER THINKING • First order: Acquire → get customers + feature • Second order: Get customers → must integrate → team distracted → core product neglected → new players eat market share • Alternative second order: Build → 12 months delay → but team velocity never drops → ship 4 other features while building this → market position strengthens MENTAL MODEL 3: OPPORTUNITY COST • Acquire: 2.8M cash + 4 engineers for 6 months (integration) • Build: 0 cash + 6 engineers for 12 months • The 2.8M could fund: A competitive marketing campaign (1.2M) + top-tier engineering hire (300K/year, 2-3 years) + product experimentation budget (1.5M) • The 6-month gap gives competitors time to launch similar features MENTAL MODEL 4: OPTIONALITY • Acquire now (1 year): Lock in customer base, close off competitor, move fast • Build and wait (1 year): Keep cash, test market demand for the feature, can still acquire later • Acquiring later is only possible if the competitor doesn't get acquired first FINAL RECOMMENDATION: BUILD • Opportunity cost (2.8M in growth investments) beats acquisition cost • Market risk of waiting 12 months is lower than integration risk of acquisition • If this feature becomes clear winner in 6 months, revisit acquisition then KEY ASSUMPTION TO MONITOR: Is the competitor's customer retention rate above 90% annually?
About this skill
Naming mental models is easy; using them correctly is not. This skill picks the few that fit your decision, runs each one with your numbers, and checks for the ways each is usually misapplied.
What it does
- Selects 3-4 models by the shape of the decision: irreversible, sunk cost, forecast-heavy, or outside your expertise
- Applies inversion, base rates, expected value, opportunity cost, reversibility, and more with concrete numbers
- Checks each model's known misuse, like a flattering reference class or ignoring ruin in expected value
- Names which model changed the answer, and where two models conflict
- Ends with one recommendation and the question to answer first
What you get
A short model-by-model breakdown, what changed, a recommendation, and a check-first item.
Best for
Founders and operators who want a sharper lens on one decision without a full framework or memo.
SKILL.md preview
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name: decision-making-mental-models
description: Run a decision through the 3-4 mental models that actually fit it - inversion, second-order effects, opportunity cost, reversibility, base rates, expected value, sunk cost, margin of safety, circle of competence, Chesterton's fence, regret minimization - applied correctly with each model's known misuses checked, and say which model changed the answer. Use when the user says "run this through some mental models", "what would inversion say here?", "am I falling for sunk cost?", "what's the base rate for this?", "second-order effects of this?", "poke holes using first principles", or "which thinking tools apply to this decision?".
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