Can you restrict which OSM tags are returned by Overpass API?

You can easily achieve this via CSV output. Read more about it in the Overpass QL documentation.

[out:csv(::id, ::lat, ::lon, name)];
area["ISO3166-1"="AD"][admin_level=2];
node[place=town](area);
out center;

Try it out: http://overpass-turbo.eu/s/qag