Based on a few simple tests, it appears that Search in Marketplace does not show results if the search words are only present in the 'Extended Description' field (alternatively called the 'Details' tab). It does not have to be a high-priority result, since a lot of out-of-context words may appear in it, but to omit search results even if those words are in that body of text is really weird.

I know there is a keyword list, but if you have to mention everything in there, (i) you run the risk of being accused of keyword spam even if your intentions are well and (ii) if the product is feature rich, you could potentially end up having to rewrite half of what you wrote in the product description text.

I don't mind ending down low on a search result list because my pack with 100 fish species also contains a herring, but 'herring' mentioned once in a body of descriptive text, but not at all showing up in a search result is kinda insane.