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Skills · Before you start

Premortem

Imagines your plan has already failed, works out why, and helps you fix those weak spots before you start.

When to use it

Before a project, launch or decision that matters. It pretends the whole thing went wrong, lists the likeliest reasons, and turns them into a better plan and a short checklist.

A real example

This is a real run, in a fresh Claude Code install with only this skill, on 30 Sep 2026. The reply is shortened: […] marks where we cut. Nothing is reworded.

What we asked

Use the premortem skill on this plan: I will run a free two-hour Saturday workshop at my local library teaching 12 retirees to use AI to write letters. I will bring my laptop and a projector, and people bring their own phones. Keep it short.

What it said back

It's six months from now. The workshop happened — and it didn't go the way you hoped. Here's why. 1. Device chaos ate the clock. A mix of iPhones, Android phones, old OS versions, and different apps meant half the room needed individual troubleshooting before anyone typed a word. […] Hidden assumption running through all of this: that "showing up with a phone" is the same as "being ready to participate." The real bottleneck isn't AI or letter-writing — it's phones, logins, and comfort.

What it can touch

Only what you paste into the chat — no files, web, or commands. It writes its report in the chat, and only saves a file if you explicitly say yes.

Install it

Download premortem.zip

In Claude (website or desktop app)

  1. Download the zip below. Keep it zipped: it already holds the premortem folder with its SKILL.md inside.
  2. In Claude (the website or the desktop app), go to Customize > Skills, click +, then Create skill, then Upload a skill, and choose the zip.
  3. On the Free, Pro or Max plan, code execution has to be on for skills to work. Turn it on in Settings > Capabilities.
  4. Start a new chat and describe the job. Claude uses the skill when it fits, or you can ask for it by name ("use the premortem skill").

From Claude’s help page, Use skills in Claude. Menus move now and then; if these don’t match, check there.

In Claude Code

  1. Download the zip below and unzip it. You get a folder called premortem.
  2. Move that folder into the .claude/skills folder in your home folder, so you end up with ~/.claude/skills/premortem/SKILL.md. (~ means your home folder. Make the skills folder if it isn’t there yet.)
  3. In Claude Code, type /premortem to use it, or just describe the job and Claude will pick it when it fits. If it doesn’t show up, start a new session.

From the Claude Code docs, Extend Claude with skills.

Reviewed on 30 Sep 2026 by three independent reviewers: one looked for hidden instructions, one for personal details, and one for what the skill can touch.