I tripped and my shoe went bouncing down the steps
Did you slip while your feet were on the stairs?
Yes, I was feeling quite tired and my foot slipped
It's normal to be clumsy sometimes, but you have to be more aware of your surroundings. The stairs is where many accidents and even many deaths, because it is so dangerous to fall down there.
The stairs are really slippery
If this is a place that you walk through regularly, you should be aware which stairs tend to be slippery.  It sounds like your shoes were loose, so maybe it would be a good idea to wear something that is easier to walk in.