I love the band Tool.  Are you familiar with them?
Yes. They are an American rock band originally from Los Angeles, California!
I remember their first big hit was Sober.
Yes they are quite popular. Tool has won three Grammy awards, performed in tours worldwide, and have had albums that were at the top of the charts in more than one country
Their singer is currently the singer of the band A Perfect Circle.
Yeah, A perfect circle is another american rockgroup formed in 1999 what has a guitarist named billy howedel and the Tool vocalist Maynard James Keenan you are right!
I forget, what is the name of Tool's second album?
Ænima is considered their second album made in 1996!
That was such a good album even better than Undertow.
Yeah Ænima was really the album that put their mark in the alternative metal movement. A lot of people will agree with you!