Then who do you mean by "government"? Are you applying for something? Or if it's just a general question, what are you exactly afraid of?
As long as your new job does not conflict with any restrictions on your Work Permit, that you have valid SIN and you pay your taxes and the job conforms to basic work regulations that government does not care what your duties are.
Ok, to be honest, my wife is working in pastry&deli but they also have a kitchen, so sometimes she cooks. Of course she doing also some other staff. I'm wondering that her empleyer could provide a letter of references which describes her job duties as a cook? Thats why I ask a previous question.
If your question is - does an employer have to describe job duties in a letter for someone who wants to apply for permanent residence, then, YES.
The letter needs to describe main duties. If cooking is not her main duty, then she would not be able to apply as a "cook." It has to be truthful, otherwise it is fraud.