Astronomer,

In the sentence you wrote "a description" does sound better than "the description" but either way is OK. Normally "the" refers to only 1 description. And "a" suggests that this is 1 description but it may not be the only description.

"I wasn't wanting" and "I was wanting" sound a bit awkward but I do understand these, so they are OK. Maybe "I didn't want" and "I did want" or "I wanted" sound better in your text.

Maybe: A silent, beautiful morning, a bird chirping and singing.