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

I am having trouble measuring some of the guidelines in:
https://play.google.com/about/storelisting-promotional/metadata/

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:

https://play.google.com/store/apps/details?id=com.dmit.plmi

https://play.google.com/store/apps/details?id=com.symbolic.pitchlab