Words that carry information
The harvest year and season, which for green tea is the most useful thing on the packet. The specific origin — an estate, a village, a mountain — rather than a country. The cultivar, where given. The grade, in the systems that have one. And the plain ingredient list, which tells you whether you are buying leaf or leaf plus flavouring.
Words that carry almost none
Premium, finest, hand-picked, artisan, reserve, and imperial are unregulated everywhere that matters. Single origin means only that the tea came from one place, which may be a country the size of China. Natural flavouring is a legal category that covers a great deal of ground. None of these is a lie; none of them is evidence either.
The ingredient list is the honest part
If a jasmine tea lists 'green tea, natural flavouring', it was sprayed rather than scented with flowers. If a fruit infusion lists apple, hibiscus and flavouring, the fruit you can see is mostly apple and the taste is mostly the flavouring. Ingredient lists are regulated in a way marketing copy is not, which makes them the most reliable text on the packet and the smallest.
Dates
A best-before date on tea is a flavour estimate, not a safety statement, and packers set them very differently. A harvest date tells you far more and is much rarer. If a green tea gives a best-before two years out and no harvest date, you are being told nothing useful about freshness.