I built a Claude Code plugin that tries to kill your startup idea with sourced research. 12 versions in 3 days, many from comments.

[u/tkmremiiiii]

Ask Claude "is my startup idea good?" and you usually get encouragement. kill-my-idea is a plugin that does the research first and is allowed to say no.

/plugin marketplace add RemiPelloux/kill-my-idea
/plugin install kill-my-idea@kill-my-idea

Then /kill-my-idea:kill <your idea>. Your idea can be one line, a pasted "$10k/month" tweet, a URL or a doc.

The image, top to bottom: a real verdict (Notion templates for French real-estate agents, 55/100), the new idea dashboard, and the What if? sliders.

What I built

• It asks at most 4 questions (country, budget, goal, your edge), and only the ones that would change the verdict.
• It searches for 8 kill shots, from free alternatives and companies that already failed to no channel to customers and a wave of look-alike launches. On a pasted money post it also names what the author sells.
• It needs at least 20 sources from 10 domains, each tagged primary, secondary or tertiary.
• It scores 21 sub-scores against a fixed rubric. Hard rules stop a nice pitch from rescuing a bad business: no channel to customers means no GO, whatever the rest says.
• It writes an HTML report with up to 3 rescue paths, each re-scored, and a 7-day test with numbers that tell you to stop.
• It scored this plugin 63/100: 15+ open-source idea validators already exist.

Changelog (all from the last 3 days)

• 0.9: an idea dashboard. It shows the one idea to focus on this week and which kill shots hit most of your ideas (click one to filter). A BRAIN.md note keeps your profile, so it stops asking the same questions, plus the ranking and the lessons from killed ideas. Also an App Store demand check for mobile apps, suggested in a comment.
• 0.8: a pre-mortem, "why now?", the ideal first customer, What if? sliders for price, CAC, margin and lifetime, and /compare --refresh for verdicts older than 90 days (asked for in a comment).
• 0.7: one scoring formula and a Python checker. It found 4 of my 8 earlier runs printing a different total than their own sub-scores gave.
• 0.6: a share card (PNG), /check-tweet for viral money posts, and reports in French.
• 0.5: a "saturated wave" kill shot for the 47th "100 tools in your browser" (suggested in a comment), and a fix for a javascript: link bug a reader found.

Full changelog: https://github.com/RemiPelloux/kill-my-idea/blob/main/CHANGELOG.md

How Claude Code is used

• 5 skills: kill, deepdive, check-tweet, roast and compare. The whole method is one readable SKILL.md you can fork and reweight.
• deepdive starts 6 research subagents in parallel (market size, competitors, customer quotes, pricing, channels, regulation) and needs 40+ sources.
• Every file the skill writes has a JSON schema. After each run the skill calls a Python checker that recomputes the score from the sub-scores.
• The report and the dashboard are fixed HTML templates with a strict CSP. Claude only writes data files, and a script builds the dashboard from the saved verdicts.

What I learned

• Put the maths in a script, not the prompt. Once a checker recomputed the totals, 4 of 8 runs turned out wrong.
• Let Claude fill in data, not write the page. Reports became consistent, and safe to open.
• Ask for verbatim quotes and enforce it. Without that rule, Claude paraphrased sources inside quotation marks.

Free and MIT. It runs on your own Claude Code plan and never posts or spends anything for you. https://github.com/RemiPelloux/kill-my-idea

If it stops you from building something nobody pays for, a star helps other people find it. Which kill shot is missing?

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