Hreflang and international SEO audit, validation, and generation. Detects common mistakes, validates language/region codes, and generates correct hreflang implementations.
SkillScore77Maintained
Automatic
◆Marketing & Content pack
Last verified 8/15/2026
What it changes
Passed 17 of 22 test cases with the skill, and 10 of 22 without it.
Without skill45%
With skill77%
Checks it passed that the model alone missed
Categorize missing return tags as Critical severity.
Categorize a missing x-default tag as High severity.
Categorize missing self-referencing tags as Critical severity.
and 6 more in the full report
7 fixed10 passed either way5 still failing0 broke
Pass-rate lift
+32 pp
Tokens
+119%
Agent turns
0%
Response time
-30%
Model gemini-3.6-flashMeasured 8/15/2026v217 of 22 cases passed with skill
Tokens, turns and time describe resource use, not a dollar price.
See it in action
One of 7 test cases the skill fixed. Same model, same prompt, with and without the skill.
1 of 7
Prompt
We operate a site targeted to `en-US`, `en-GB`, and `fr-FR`. Users arriving from Spain or Japan currently receive non-localized errors because no fallback page is declared. What specific tag attribute must be added, and what severity is assigned if it is missing?
What was checked, without and with the skill
Checked
Without skill
With skill
Identify x-default as the tag attribute used to specify the fallback page for unmatched languages or regions.
Passed
Passed
Categorize a missing x-default tag as High severity.
Missed
Passed
case-16 · gemini-3.6-flash · 8/15/2026 · answers are capped and redacted
What's inside
The instructions your model reads when the skill loads.
SKILL.md241 lines5 files
Hreflang & International SEO
Validate existing hreflang implementations or generate correct hreflang tags
for multi-language and multi-region sites. Supports HTML, HTTP header, and
XML sitemap implementations.
Validation Checks
1. Self-Referencing Tags
Every page must include an hreflang tag pointing to itself
The self-referencing URL must exactly match the page's canonical URL
Missing self-referencing tags cause Google to ignore the entire hreflang set
2. Return Tags
If page A links to page B with hreflang, page B must link back to page A
Every hreflang relationship must be bidirectional (A→B and B→A)
Missing return tags invalidate the hreflang signal for both pages
Check all language versions reference each other (full mesh)
3. x-default Tag
Required: designates the fallback page for unmatched languages/regions
Typically points to the language selector page or English version
Only one x-default per set of alternates
Must also have return tags from all other language versions
4. Language Code Validation
Must use ISO 639-1 two-letter codes (e.g., en, fr, de, ja)
Common errors:
eng instead of en (ISO 639-2, not valid for hreflang)
jp instead of ja (incorrect code for Japanese)
zh without region qualifier (ambiguous; use zh-Hans or zh-Hant)
5. Region Code Validation
Optional region qualifier uses ISO 3166-1 Alpha-2 (e.g., en-US, en-GB, pt-BR)