Hi Friend,
I believe, there is no tool to determine this automatically. You will have to manually see (in summary page ESXi host) that how much cpu/memory is being used by other hosts, note down + how much mem/cpu is being used by the host which you want to put into MM. This will give you fair idea on whether all you VMs can be accommodated on all other hosts.
In addition to this. you will have to check HA/DRS (specially DRS threshold + DRS rules)/DPM/SDRS configuration so that these features will not be affected.