Front-End Checklist is a collection of front-end web development rules organized as a practical review and quality workflow for people and AI agents. Developers use it to audit projects and pull requests, check implementation details, and find guidance for remediation and verification. The catalogue entries provide skills, instructions, MCP tools, and a plugin for using the checklist in agent workflows.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add thedaviddias/Front-End-Checklist --skill canonical-chaingit clone --depth 1 https://github.com/thedaviddias/Front-End-ChecklistWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/thedaviddias/front-end-checklist/canonical-chain)<a href="https://agentmods.dev/skills/thedaviddias/front-end-checklist/canonical-chain"><img src="https://agentmods.dev/badge/skills/thedaviddias/front-end-checklist/canonical-chain/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/thedaviddias/front-end-checklist/canonical-chain"><img src="https://agentmods.dev/badge/skills/thedaviddias/front-end-checklist/canonical-chain.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00041 | $0.00348 |
| Opus 5.5 | $0.00016 | $0.00139 |
| Sonnet 5.5 | $0.00008 | $0.00070 |
| Haiku 4.5 | $0.00004 | $0.00035 |
Grade A, and why
canonical-chain scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
What it actually says
Avoid redirect chains on canonical URLs
Canonical chains confuse search engines and can result in the wrong version of a page being indexed, while also adding unnecessary latency for crawlers.
Quick Reference
- Ensure that the URL in your
rel="canonical"tag returns a 200 OK status - Never point a canonical tag to a URL that then redirects to another location
- Verify that the canonical URL is the final, intended version of the content
Check
Verify that the canonical URL of the page does not result in any redirects.
Fix
Update the <link rel="canonical"> tag to point directly to the final, non-redirecting URL.
Explain
Explain why pointing a canonical tag to a redirecting URL weakens the canonical-url signal and impacts SEO.
Code Review
Review metadata generation, rendered HTML, structured data, and response headers related to Avoid redirect chains on canonical URLs. Flag exact routes or templates where search-facing output violates the rule, and describe how to verify the final page output.
For full implementation details, code examples, and framework-specific guidance,
see references/rule.md.
Rule page: https://frontendchecklist.io/rules/seo/canonical-chain
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago Changed 0b8ce8ebc002
- 2mo ago First seen · 45 lines · 41 tokens per session scan A af11e50acfbd
canonical-chain is a skill published in the GitHub repository thedaviddias/Front-End-Checklist (74,658 stars, last pushed 6d ago), licensed MIT. It adds 41 tokens to every session and 348 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
canonical-chain compared with skills from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| canonical-chainthedaviddias/Front-End-Checklist | Skill | 75k | 6d ago | MIT | A | 41 | Claude Code, Codex |
| scalar-design-systemscalar/scalar | Skill | 16k | yesterday | MIT | A | 68 | Claude Code, Codex |
| citation-verificationGalaxy-Dawn/claude-scholar | Skill | 6.0k | 18d ago | MIT | A | 63 | Claude Code |
| stopoversborski/travel-hacking-toolkit | Skill | 895 | yesterday | MIT | A | 62 | Claude Code |
| flight-search-strategyborski/travel-hacking-toolkit | Skill | 895 | yesterday | MIT | A | 48 | Claude Code |
| alliancesborski/travel-hacking-toolkit | Skill | 895 | yesterday | MIT | A | 39 | Claude Code |
| design-loopericrisco/rsc-harness | Skill | 503 | 2d ago | MIT | A | 79 | Claude Code, Codex |