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Agent skill

404 Page

by thedaviddias in thedaviddias/Front-End-Checklist

A skill your agent uses when reviewing templates, rendered HTML, or shared components related to Create a custom 404 error page.

MITAuto-check passed

Install 404 Page

skills CLI
$ npx skills add thedaviddias/Front-End-Checklist --skill 404-page -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install thedaviddias/Front-End-Checklist 404-page --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/thedaviddias/Front-End-Checklist.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/404-page .claude/skills/404-page && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
404-page
GitHub stars
74k
Token cost
~461 tokens
SKILL.md length
213 words
Files
2 (incl. references)
Skills in repo
390
Repo updated
First seen
Licence
MIT

At a glance

A skill your agent uses when reviewing templates, rendered HTML, or shared components related to Create a custom 404 error page.

  • Reviewing templates
  • SKILL.md covers Quick Reference, Check, Fix and Explain, plus 1 more section
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
  • Shared components related to Create a custom 404 error page

What it does

404 Page is an agent skill from thedaviddias/Front-End-Checklist. Use when reviewing templates, rendered HTML, or shared components related to Create a custom 404 error page. Validate the final browser-facing markup, not just the source framework abstraction.

Its SKILL.md is about 460 tokens, which your agent loads only when the skill is triggered. The skill folder holds 2 other files, including reference files (for example `references/rule.md`).

The repository describes itself as: 🗂 The essential checklist for modern web development, for humans and AI agents. The licence is MIT.

When your agent uses it

  • Reviewing templates
  • Shared components related to Create a custom 404 error page

Example prompts

  • “/404-page”

What it can do on your machine

Read from SKILL.md and the folder at commit e8d14d0. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md.

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    Links to these hosts (documentation or services it may open):

    • frontendchecklist.io

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

404 Page loads about 461 tokens when it runs, and up to ~2.2k if it reads all its reference files. Until then it costs about 51 tokens; SKILL.md has 213 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~51
When it runs · the whole SKILL.md, loaded when a task matches
~461
With references · SKILL.md plus every file in references/, read only if the agent opens them
~2.2k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from thedaviddias/Front-End-Checklist at commit e8d14d0, republished under its MIT licence (© thedaviddias). 213 words, ~461 tokens.

Download SKILL.mdSave it as .claude/skills/404-page/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.
name
404-page
description
Use when reviewing templates, rendered HTML, or shared components related to Create a custom 404 error page. Validate the final browser-facing markup, not just the source framework abstraction.
metadata.category
html
metadata.priority
medium
metadata.difficulty
beginner
metadata.estimatedTime
20
metadata.source
frontendchecklist.io
metadata.url
https://frontendchecklist.io/rules/html/404-page

Create a custom 404 error page

A generic browser 404 page causes users to leave immediately—a well-designed custom page provides recovery paths and keeps users engaged with your site.

Quick Reference

  • Custom 404 pages retain users who encounter broken or moved links
  • Include search, navigation, and links to popular content
  • Maintain consistent branding and site design
  • Track 404 errors to identify and fix broken links
  • Return a real HTTP 404 so the page is not treated as a soft 404

Check

Verify that this website has a custom 404 error page with helpful navigation options. Confirm the route returns HTTP 404 and not a branded page with a 200 response.

Fix

Create a user-friendly 404 page with search functionality and links to important pages. Ensure the server or framework returns status code 404 so the page does not become a soft 404.

Explain

Explain how custom 404 pages help retain users who encounter broken links and why returning 200 for missing pages creates soft-404 indexing problems.

Code Review

Review templates, server-rendered HTML, and shared components that output markup related to Create a custom 404 error page. Flag exact elements, attributes, and routes where the rendered HTML violates the rule.

For full implementation details, code examples, and framework-specific guidance, see references/rule.md.

Rule page: https://frontendchecklist.io/rules/html/404-page

© thedaviddias, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 1 other file (references) in skills/404-page of thedaviddias/Front-End-Checklist.

  • SKILL.md
  • references/rule.md

Open the folder on GitHubat commit e8d14d0

Compare with similar skills

404 Page next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

404 Page compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
404 Page this skillthedaviddias/Front-End-Checklist74k—~461Automated safety check: PassMIT
RenderLeoYeAI/openclaw-master-skills2.2k—~4.8kAutomated safety check: PassMIT
Markdown Renderingsickn33/agentic-awesome-skills47k1 repos~751Automated safety check: PassMIT
RenderAnil-matcha/awesome-muse-connectors1.3k—~433Automated safety check: PassMIT
Web Renderer Testremotion-dev/remotion63k—~547Automated safety check: PassCustom licence
Render HTMLwanshuiyin/Auto-claude-code-research-in-sleep17k1 repos~5.4kAutomated safety check: NotesMIT

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Questions about 404 Page

What does 404 Page do?

A skill your agent uses when reviewing templates, rendered HTML, or shared components related to Create a custom 404 error page. 404 Page is an agent skill from thedaviddias/Front-End-Checklist. Use when reviewing templates, rendered HTML, or shared components related to Create a custom 404 error page.

When should I use 404 Page?

404 Page fits situations like: reviewing templates; shared components related to Create a custom 404 error page.

How do I install 404 Page in Claude Code?

Run `npx skills add thedaviddias/Front-End-Checklist --skill 404-page -a claude-code`. Or copy the skill folder (skills/404-page in thedaviddias/Front-End-Checklist) into .claude/skills/404-page in your project. Claude Code loads it when a task matches its description.

How do I install 404 Page in Codex?

Run `npx skills add thedaviddias/Front-End-Checklist --skill 404-page -a codex`. Or copy the skill folder (skills/404-page in thedaviddias/Front-End-Checklist) into .agents/skills/404-page in your project. Codex loads it when a task matches its description.

Can I use 404 Page in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add thedaviddias/Front-End-Checklist --skill 404-page -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/404-page, .gemini/skills/404-page, .github/skills/404-page and .opencode/skills/404-page in your project.

What does 404 Page need to run?

SKILL.md names no scripts, command-line tools or credentials: 404 Page is instructions for the agent only.

Does 404 Page access the network?

SKILL.md names 1 domain. As links in the text: frontendchecklist.io. This is read from the text; nothing was executed.

Is 404 Page safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does 404 Page use?

404 Page is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does 404 Page use?

About 461 tokens (SKILL.md is roughly 1.8k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 1.8k tokens, read only when the agent opens those files.

What are the alternatives to 404 Page?

Skills that share tags, products or a category with 404 Page: Render (LeoYeAI/openclaw-master-skills, 2.2k stars), Markdown Rendering (sickn33/agentic-awesome-skills, 47k stars), Render (Anil-matcha/awesome-muse-connectors, 1.3k stars) and Web Renderer Test (remotion-dev/remotion, 63k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains 404 Page?

thedaviddias (a GitHub user) maintains it in thedaviddias/Front-End-Checklist, which has 74,421 GitHub stars. The repository holds 390 skills in this directory. The repository was last updated on October 6, 2026.

Source: thedaviddias/Front-End-Checklist on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.