I like to think of "adequate" as a relative term. If you can comfortably play all the music you currently have (e.g. horn parts for the ensemble you may be in, etude books, solos), then you're okay in my book. If you have a private instructor or ever get one, they will be a better judge because they can hear you firsthand. How long were you playing trumpet for?
There are plenty of other posts that ask this same question. Search through the forum to see if you can find anything of use. Here's a short list of things I found through a quick query of "highest" (since brass players often like to talk about how high they can play):
http://8notes.com/f/51_146988.asp
http://8notes.com/f/51_237655.asp
http://8notes.com/f/51_238133.asp
