Instances where XenServer encounters various errors while installing XenServer VM tools
CTX236718 - XenServer 7.1 "I/O not optimized" and "management agent not installed" error
CTX230699 - XenServer - 7.1 - Unable to Install XenTools on Windows VM
CTX212400 - XenCenter shows "XenServer tools not installed" even though the Tools are updated.
In different situations, XenServer has some issues when installing VM tools, possibly due to various factors. This article will outline different scenarios and potential solutions