How can tags get you in trouble on YouTube????
You can get the video marked as spam if its in the description, and possibly taken down giving you a strike. That's why there is a Tag spot to place all your tags which is a Max of 500 Characters.
More info via Fullscreen :
"Content creators! You may be aware already, but a heads up: over the last few months, YouTube has been issuing community strikes on videos that contain tag spam—unnecessary and excessive tags in their descriptions. So we wanted to let you know how you can avoid violating YouTube’s policy while still driving traffic effectively to your videos.
You might assume that stuffing your video descriptions with extra keywords will help your YouTube search ranking—but the reality is quite the opposite. Too many extra keywords can not only
hurt your videos’ search ranking but can also result in a strike against your account.
Here’s an example of tag spam:
YouTube
has shut down some channels who violate its tag spam policy—regardless of channel size. We’ve seen both small and large channels suspended for excessive tag spam."
I can't link it which is why i put part of it on here... Highlight some text and search with google to find full Article.