Poor keyword search results - what am I doing wrong?

What version of Photos are you running.

That has been a know shortcoming of previous Photos versions.

To work around create a Smart Album with the criteria:

Keyword is XXXXX

See if that will give you a more accurate finding.

However, with Photos 5.0 I get the same results plugging my XXXX into the search field as I get with a Smart Album.

I have been using the keyword "art" to tag photos of artwork that my son brings home from school. When I type "art" into the search box, it comes up with 1,558 photos...

The search field in Photos 5 does no longer allow you to search specifically for a keyword. It will turn up everything that is related to "art" in some sense, if you search for for "Art", any text containing "Art", or photos in the category "Arts & Entertainment", which will give surprising results.

In Photos 5.0 you can get more specific search results, if you use the filter instead of the search field. Just add the keyword "Art" to the Quick Group in the Keyword Manager. Then you can filter any view or album to turn up just the items with the keyword "Art" by setting the "Showing Only" filter to "Art".

I had two keywords for the same person, one just a first name and one with both names. That somewhat messed up the search box search. I removed the full name keyword and now get same results both ways.