To expand on what Maneesh said, Eclipse itself doesn't know anything at all about J2EE or Tomcat. However, one of the standard Eclipse downloads does come with J2EE development support plug-ins pre-installed. One of those plug-ins is the WTP plugin and it can run Tomcat, although it does a horrible job of it. Which is why Maneesh and myself prefer to install the sysdeo Tomcat plug-in and ignore WTP server/webapp management altogether.
There are, I think, other Tomcat interface plug-ins out there as well, but I don't have firsthand knowledge of any of them.
An IDE is no substitute for an Intelligent Developer.