Answer:
The very first descriptive adjectives Twain uses to describe Miss Watson are "tolerable", "slim", and "old". These three give a very clear picture about Miss Watson before even going into detail. It allows the reader to imagine what she would look like, probably having an idea of an old thin woman already in their head. Then, Twain goes on with his description by saying she worked Huck "middling hard" which shows that she is starting to become a bit less tolerable and a bit more demanding of what she wants from him. As their interaction goes on it is clear that Huck is less and less comfortable and Miss Watson becomes more and more sharp in addressing him.
Explanation:
Twain uses descriptive adjective to characterize Miss Watson by using words like "a tolerable slim old maid" and explain her teaching ways. Twain gave a clear description of what Miss Watson looks like, but also how she acts and teaches children, especially Huck. You can see that in this excerpt, she is always telling Huck how to behave: ""Don't put your feet up there, Huckleberry;" and "Don't scrunch up like that, Huckleberry-set up straight;"".
