When do we need to upgrade vmware tools?
VMware Tools upgrade is optional, BUT is always recommended... you can read more about in this blog article: Is a VMware Tools Upgrade Required When Upgrading vSphere? | VMware vSphere Blog - VMware Blogs
Welcome to communities.
you can configured auto upgrade, please follow below KB
then why vmware tools hows "out of date"
Because the version does not match the version available on the host.