Canonical URL
Businesscanonical-urlCanonical URL is an Agent Skill for business published in the thedaviddias/Front-End-Checklist repository on GitHub: a SKILL.md instruction file an AI agent can load to do this task.
Use when auditing metadata, crawlability, structured data, or indexability related to Set canonical URLs for all pages. Verify the rendered HTML and HTTP response rather than relying only on source files.
How to use this skill
Bring this guide into your coding agent with a prompt tailored to the tool you use.
- Open your project in Codex.
- Copy and paste the prompt below.
- Review files and risks before approving any action.
Inspect the Agent Skill at https://github.com/thedaviddias/Front-End-Checklist/blob/HEAD/skills/canonical-url/SKILL.md and all supporting files. Report provenance, permissions, scripts, dependencies, and security risks. Propose an exact installation into .agents/skills/canonical-url, but wait for my approval before writing files or running scripts.
Copying this prompt does not install or run the skill. Review third-party files before use.
Set canonical URLs for all pages
Duplicate content from URL parameters, www vs non-www, or pagination dilutes ranking signals—canonical tags consolidate these signals to the preferred URL.
Quick Reference
- Canonical URLs tell search engines which version of a page to index
- Prevents duplicate content penalties from URL variations
- Use absolute URLs including protocol and domain
- Self-referencing canonicals are a best practice
Check
Verify that this page has a canonical URL tag and that it points to the correct preferred version.
Fix
Add or correct the canonical URL tag in the head section to prevent duplicate content issues.
Explain
Explain how canonical URLs help search engines understand the preferred version of duplicate or similar pages.
Code Review
Review metadata generation, rendered HTML, structured data, and response headers related to Set canonical URLs for all pages. 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/en/rules/seo/canonical-url