When the user wants to create, optimize, or audit 404 error pages. Also use when the user mentions "404 page," "404 error," "error page," "page not found," "broken link page," "404 design," "custom 404," "404 redirect," "404 page UX," or "404 recovery." For sitewide page planning, use website-structure.
SkillScore95Maintained
Automatic
◆Design & UX Review pack
Last verified 8/14/2026
What it changes
Passed 21 of 22 test cases with the skill, and 17 of 22 without it.
Without skill77%
With skill95%
Checks it passed that the model alone missed
Includes a design checklist section.
References homepage-generator as the main escape route.
References brand-visual-generator for visual identity tokens.
and 1 more in the full report
4 fixed17 passed either way1 still failing0 broke
Pass-rate lift
+18 pp
Tokens
+15%
Agent turns
0%
Response time
-20%
Model gemini-3.6-flashMeasured 8/14/2026v1 · latest is v221 of 22 cases passed with skill
Tokens, turns and time describe resource use, not a dollar price.
This benchmark measured an earlier version of the skill.
See it in action
One of 4 test cases the skill fixed. Same model, same prompt, with and without the skill.
1 of 4
Prompt
Which primary site page generator serves as the main escape route destination for lost visitors on a missing page?
What was checked, without and with the skill
Checked
Without skill
With skill
References homepage-generator as the main escape route.
Missed
Passed
case-21 · gemini-3.6-flash · 8/14/2026 · answers are capped and redacted
What's inside
The instructions your model reads when the skill loads.
SKILL.md9 linessingle file
404 Page construction has moved
404 Page construction is now maintained in the 404 Page reference in Pagina, the page intelligence layer for AI agents.