+John Mueller 
I'd like to ask you a question about mobile friendly.

Which barometer can ensure that a webpage is recognized as fully mobile-friendly one by google? 

There are many sigals/tools Google offer for mobile-friendliness.

1: "Mobile-Friendly" label on SERPs
2: "Mobile Friendly Test" tool
3: "Mobile Usability Report" in GWT.
4: PageSpeed Insight

As long as I've learned from you and other Googlers, 1/2/3 are based on similar or the same mechanism using Googlebot, and 4 is different using more user-like setting.
But in some cases, results of 1/2/3 can be inconsistent.
In forum, there are feedbacks that pages passed MFT got mobile usability warning message on GWT, or can't get "Mobile-Friendly" labels.

Which one is most suitable checkpoint to confirm that a webpage is recognized as a perfectly mobile-friendly page by Google?


e.g. Forum threads reporting inconsistency.
English
https://productforums.google.com/forum/#!searchin/webmasters/WNC-451500|sort:date/webmasters/Fi4M1pCjItI/dXezoCNDkhAJ

Japanese
https://productforums.google.com/forum/#!category-topic/webmaster-ja/vZZXRugPoEM
https://productforums.google.com/forum/#!searchin/webmaster-ja/モバイル|sort:date/webmaster-ja/Y-LcEi71kWo/ZzpJLePWc_4J
https://productforums.google.com/forum/#!searchin/webmaster-ja/モバイル|sort:date/webmaster-ja/WPPk0_PZaOw/xyHD070sDcYJ
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