I worked as a nanny for a number of years. I made sure that my responsibilities (which we mutually agreed on) were in the contract, so that we both had something to refer back to in case of misunderstandings.
Because my background is in early childhood ed, people were hiring me primarily to care for the kids. This meant that I would ensure we had age-appropriate projects, outings and activities. I also wrote into my contract that we had a maximum of 1 hour of tv daily unless the child/ren were sick. They were getting what they were paying for.:)
Household tasks I was responsible for: any of the messes I made with the kids would be cleaned. (Clean-up after arts/crafts). I did all the kid-related dishes;prepped/cleaned up after meals. Swept the kitchen at least once a day, because they're messy eaters. Spot cleaned drips and drops from eating. Ensured kids got their snacks and meals at their usual times. Kept to the family schedule. Helped kids with making their beds/picking up their rooms. Organized the playroom/art shelves. Would fold/put away kids laundry with the kids helping. Helped kids with gardening tasks (when appropriate) and took them out to the park, library, playtimes, etc.
All of the families had a separate housekeepers who would come once a week to do floors/deep clean the bathroom. I worked to ensure that the kids' rooms were picked up for this, their floors were clear for vacuuming, and the kids were out of the housekeepers way.
Most of the moms did not have me do any meal prep, however, they might call and ask me to set out a healthy snack for the kids if they were running late, or ask me to pull something out of the freezer to defrost. There were other times, too, if the kids were older, that we would make dinner as an activity for the day, something like a pasta dish or shepherd's pie, but again, that was a bonus. I also, nearly always did the breakfast dishes; it gave me a break from one-on-one interaction (and the kids need these sorts of times, they don't need me to be an entertainment machine, so I'd set them up with playdough and do the dishes while they played). Besides, those dishes would have just gotten in my way. That said, I never wrote it into my contract, because sometimes kids get sick or we have an extra-busy day and my first priority was always the children. Dishes can wait!