VMware tools is software that negotiates between the Operating System (OS) and the virtual environment. It provides improved functionality in the operation and management of the virtual machine (for example: automatic grabbing and releasing of the mouse cursor) and drivers for the virtual hardware. Installing this feature is strongly recommended. MiServer managed VMs have tools installed by default.
For managed servers, upgrades will be handled by the Linux/Windows MiServer teams. For non-managed servers, server admins will need to run the upgrade on their VMs.
Visit the VMware Knowledge Base for instructions on how to upgrade VMware Tools.