"a good pen" is correct and usable in written English.
You can use it to describe a writing instrument, like "I need to buy a good pen for writing letters."
Things that have not been seen for some time: a good pen, a souvenir key ring.
Recognizing patterns is part of the film critic's tool kit along with a good pen to take notes in the dark.
Picking the right stock of paper, using a good pen and choosing interesting stamps are all part of the dwindling art of letter writing.
You're going to bring a leather or vegan leather portfolio with a full notepad in it, a good pen and a few of your paper resumes to the interview.
"I also think that there are so few options available for a good pen at a decent price at present that we office monkeys are willing to help fund projects to give us what we want.
In addition, some better-off farmers already had a good size pen so they ended up having two pens.
While it delivers a beautiful line, a good fountain pen can be pricy, and it takes a good deal of practice to perfect fountain pen technique.
If you're filling in an application form or updating your CV, print it out and hand write your answers or adjustments with a good old pen and paper.
There's nothing like a handwritten note, especially when the writing instrument is a good fountain pen.
