validate-idea

validate-idea is a skill for Claude Code, Codex from impactbrussels/FounderOS. It costs 100 tokens per session (1,071 once invoked), scanned A, original, Apache-2.0.

A structured method for testing whether a startup idea solves a real customer problem before building it. It focuses on identifying the specific customer, problem, current workaround, and riskiest assumption.

In plain words
What is it for?
Use it to write a clear problem statement, identify the ideal customer, examine existing alternatives, and design the cheapest experiment that can validate the idea.
Why use it?
It prevents spending months building something people do not need by testing the most uncertain and important belief first.

Skill for Claude CodeCodex

Part of the founderos plugin — 23 skills, 3 agents shipped together

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/impactbrussels/founderos/validate-idea
Any agent
npx skills add impactbrussels/FounderOS --skill validate-idea
Clone the repo
git clone --depth 1 https://github.com/impactbrussels/FounderOS

Made for: Claude Code, Codex.

Or install founderos, the plugin that ships this one along with the rest of its 23 skills, 3 agents.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for validate-idea

README.md
[![agentmods](https://agentmods.dev/badge/skills/impactbrussels/founderos/validate-idea.svg)](https://agentmods.dev/skills/impactbrussels/founderos/validate-idea)
Your own site
<a href="https://agentmods.dev/skills/impactbrussels/founderos/validate-idea"><img src="https://agentmods.dev/badge/skills/impactbrussels/founderos/validate-idea.svg" alt="Measured on agentmods" height="20"></a>
Per session 100 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,071 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00100 $0.01071
Opus 5 $0.00050 $0.00535
Sonnet 5 $0.00020 $0.00214
Haiku 4.5 $0.00010 $0.00107

Measured 3d ago against content hash c4ef9b27be64, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

validate-idea scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/validate-idea/SKILL.md · 83 lines

How it starts

The opening of the file, as written. The whole thing — 83 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Validate the Idea

Most startups die from building something nobody wanted - not from building it badly. Validation is the cheapest insurance a founder can buy: hours of evidence-gathering that save months of wasted building. This skill turns "I have an idea" into "here's the one assumption that decides whether this is real, and the cheapest experiment to test it."

The method

Built on the Founder OS scaffold (High tier). Full frameworks in references/validation-playbook.md.

Step 1 - Sharpen the problem (not the solution)

Founders pitch solutions; investors and customers buy solved problems. Reframe:

  • Who exactly has this problem ([ICP] - be specific; "everyone" means no one).
  • What painful job are they failing to get done today ([PROBLEM]).
  • How do they cope right now (the real competitor is usually a spreadsheet, a workaround, or nothing).
  • How often / how much it hurts - frequency × intensity = whether anyone will pay.

Output a one-paragraph problem statement in the customer's words, not yours.

Step 2 - Name the riskiest assumption

Every idea rests on a stack of beliefs. List them, then find the one that is both most uncertain and most fatal if wrong - that's the [RISKIEST_ASSUMPTION]. Common types: problem risk (do they even have it?), demand risk (will they pay/switch?), reachability risk (can you find them affordably?), solution risk (can you actually solve it?). Validate in that order - problem and demand before solution, almost always.

Step 3 - Design the cheapest test that could prove you wrong

A good experiment is falsifiable, fast, and cheap, and you commit to the pass/fail bar before running it. Match the test to the assumption:

Assumption type Cheap test Pass signal
Problem risk 5-10 customer-interviews (Mom Test style) They describe the pain unprompted, with stories
Demand risk Landing page + pre-order / waitlist / "fake door" Real sign-ups or pre-payment above your bar
Reachability One outreach channel, 20 cold contacts Reply/booking rate that could scale
Solution risk Concierge / manual "Wizard of Oz" delivery They use it and come back

Read the full file on GitHub · 83 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 3d ago First seen · 83 lines · 100 tokens per session scan A c4ef9b27be64

Subscribe to this mod's changes

validate-idea is a skill published in the GitHub repository impactbrussels/FounderOS (2 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 100 tokens to every session and 1,071 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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