The tone of the sentence, "I'm sure you'll be happy to know it looks a lot better these day" is: Optimistic.
The tone of a sentence refers to the feeling that is given off by the word choice of the writer.
In the sentence above, the speaker expressed optimism because he was positive that the listener will be happy to know about the state of the object that he was talking about.
Learn more about literary tone here:
https://brainly.com/question/15447799