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Use when auditing metadata, crawlability, structured data, or indexability related to Sync HTML canonical tags and Link headers. Verify the rendered HTML and HTTP response rather than relying only on source files.
Passed 21 of 22 test cases with the skill, and 18 of 22 without it.
3 fixed18 passed either way1 still failing0 broke
Tokens, turns and time describe resource use, not a dollar price.
This benchmark measured an earlier version of the skill.
One of 3 test cases the skill fixed. Same model, same prompt, with and without the skill.
A marketing site appends URL parameters for tracking. The server response header emits `Link: <https://example.com/pricing?utm_source=google>; rel="canonical"`, whereas the HTML meta generator strips tracking parameters and outputs `<link rel="canonical" href="https://example.com/pricing">`. What is the flaw in this response?
| Checked | Without skill | With skill |
|---|---|---|
| Identifies that the HTTP Link header includes tracking parameters omitted by the HTML tag. | Passed | Passed |
| Specifies removing marketing query parameters from both header and HTML canonical declarations. | Missed | Passed |
The instructions your model reads when the skill loads.
Conflicting canonical-url signals can lead search engines to ignore both declarations, potentially causing duplicate content issues and incorrect indexing.
rel="canonical" tag in your HTML matches the Link canonical-url header if both are usedCompare the HTML canonical tag with the HTTP Link header to ensure they point to the exact same URL.
Update either the HTML tag or the HTTP header so that they provide a consistent canonical URL signal.
Explain the risks of sending conflicting technical SEO signals to search engine crawlers.
Review metadata generation, rendered HTML, structured data, and response headers related to Sync HTML canonical tags and Link headers. 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-header
test cases passed, vs 18 / 22 without
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