Both UR5e tooling offers justify suitability using only the motor-housing mass; our proposed assembly also has extended fingers, an adapter and hose fittings (all apparently weightless in the sales explanation). What assessment should I request?
Ask for the complete held assembly, its mass distribution and relevant operating conditions assessed against the manufacturer's limits for that robot configuration. Part mass alone doesn't establish suitability. Keep the adapter, fingers and fittings explicitly included.