On the bundled sample: 7 findings (7 errors, 0 warnings) in 1 file from 13 rules, including an expired certificate and class C printed for 182 kWh/(m2*a).

Who it’s for
For developers at German property portals, estate agencies and PropTech teams who render listing pages and exposés from HTML templates.

What breaks, and when
An ad that skips a GEG Sec. 87 detail or prints the wrong class misstates the certificate; a certificate is valid ten years, so one issued 12.03.2015 expired 12.03.2025.

What you get
• SKILL.md, an offline Node scanner and the 13-rule table
• file:line, severity and the GEG duty each line misses

See it first
The real output of the bundled example is on getreadystack.com/skills/energieausweis-listing-check/ — free, no sign-up, so you see what it finds before you pay.

Install in 30 seconds
Unzip into ~/.claude/skills/, then ask Claude Code: “Check our property listing pages for the Energieausweis mandatory fields. Don’t edit anything yet.”. Needs Node 16+.

What it does not do
It cannot see your real certificate, only what the ad prints; no network calls, no edits without your OK.

FAQ
Q: How is this different from asking Claude without the skill?
A: The skill carries a dated rule table and a scanner that reads every file, so Claude quotes the exact date and line instead of guessing from memory.
Q: How do I get the files?
A: In your Whop library after paying: the lesson “energieausweis-listing-check.zip”.