For security reasons, some NFC chips like door access badges, bank / credit cards, transport cards are protected against reads and writes. Imagine if everyone could, with a simple app, copy and emulate your credit card or your access badge, it would be very dangerous.
This is why, technically speaking, it's not possible to emulate protected NFC chips.
Moreover, the Android system doesn't allow developers to define the UID that is used for emulation. This UID will be randomly generated by Android.
With NFC Tools, you can only emulate standard records like URL, TEXT, and more.
Here is a video that explains how to emulate a NFC record with NFC Tools: https://www.youtube.com/watch?v=op3B9iIuMKg