What do I need to use Assumption Mapper?

Product brief, PRD, or concept description; Stage.

Is Assumption Mapper free to use?

Yes — run it free in the browser playground (no API key needed for the sponsored trial, or bring any provider key), or install it into Claude Code, Cursor, ChatGPT and more via npx pm-claude-skills. MIT-licensed and open source.

Assumption Mapper

Q: How do I know the Assumption Mapper output is good?

The skill verifies itself against its own quality checks: At least one assumption per category (Desirability, Feasibility, Viability, Usability); All Impact 4+ / Confidence 2− assumptions flagged as CRITICAL; Each validation method is specific (not just "do research" — name the method and sample size); Priority scores are consistent (Impact − Confidence, higher = more urgent).

🟢 Production-Ready🕐 updated 2026-08-08 ✅ 5/5 🔷 SkillSpec L3 pm-discovery

Extract and risk-rate hidden assumptions in a product brief or PRD. Use when asked to review a product brief for assumptions, audit a PRD for risks, find hidden assumptions, validate product plans, or run an assumption analysis. Produces a prioritised assumption map with confidence and impact scores, recommended validation methods, and critical assumption flags.

📚 Based on Assumption testing — Testing Business Ideas (David Bland); Teresa Torres

▶ Run it free — no key needed 📝 Grade your existing draft View SKILL.md ↗

What to give it

▸Product brief, PRD, or concept description — even rough notes work

▸Stage — concept / discovery / pre-build / post-launch — affects which assumptions matter most

✅ The bar it holds itself to

Every skill in this library self-verifies — these are this skill's own quality checks, straight from its definition.

✓At least one assumption per category (Desirability, Feasibility, Viability, Usability)

✓All Impact 4+ / Confidence 2− assumptions flagged as CRITICAL

✓Each validation method is specific (not just "do research" — name the method and sample size)

✓Priority scores are consistent (Impact − Confidence, higher = more urgent)

⚠️ What it refuses to do

Do not only surface desirability assumptions — feasibility and viability assumptions are equally likely to kill a product and are often overlooked

Do not assign high confidence to an assumption just because it hasn't been challenged yet — absence of evidence is not evidence

Do not recommend "user interviews" as the validation method for every assumption — some assumptions require quantitative data, competitive analysis, or technical spikes

Do not list assumptions that cannot be tested — every assumption in the map must have a plausible validation method, or it should be flagged as unknowable and treated as a risk

Install

npx pm-claude-skills add --agent claude   # or codex · cursor · gemini · hermes
# or one-line MCP (every skill, any client):
claude mcp add pm-skills -- npx -y pm-claude-skills-mcp

Start with

Related skills

🔌 Embed this skill

Drop this on your blog, docs, or site — it renders a "Run this skill" card:

<div data-pm-skill="assumption-mapper"></div>
<script src="https://mohitagw15856.github.io/pm-claude-skills/embed.js" async></script>

💬 Discussion

Assumption Mapper is one of 1078 open-source professional AI agent skills — all SkillSpec L3. Try them all in the browser · ⭐ Star on GitHub · Browse the full catalog