well... iirc the MCC is determined by credit card companies like Visa, Mastercard, Diner and Amex.
as mcc isn't something which is widely advertised and shared, the vast majority still think that the banks are the ones which issues these mcc and they should know about it.
the mcc code given to a business or store is based on the very first time the business starts accepting one of these cards as a form of payment.
A very practical example: Cafes, Bars, Restaurants
The common mcc codes are 5811, 5812 and 5813
5811- Caterers
For: Caterers, Restaurants, Bars
5812- Eating Places, Restaurants
For: Caterers, Restaurants, Bars
5813- Drinking Places
For: Caterers, Restaurants, Bars
For shops selling watches, the mcc code should be 5094 or 5944
http://mcc-codes.findthecompany.com/
tbh, I have my own excel containing the mcc codes for each of my credit cards. these mcc codes are mainly the shops I have used my credit cards before.