When does an app's description have excessive details or excessive keywords?

I am having trouble measuring some of the guidelines in:

For example:
If i have an app about musical instruments that includes around 30 instruments and i list them on my store listing’s description, am i violating the guidelines?
I am about to publish my first app so i am quite in the dark about this. What does your experience tell you about my example?

I am confused because for example, i see some apps on google play, such as the following two, that apparently are not suspended: