Receptionist

Hello,
Thank you for reading my question.

Article use. Mandy is a receptionist at a small business.

Scenario 1. I am having dinner with my family and I am discussing Mandy, my friend.
Of course Mandy is polite. She is a receptionist/works as a receptionist, so she knows how to be friendly and polite.

Scenario 2. Same dinner. Mandy is my coworker at the business.
That Mandy is very rude. And she is the receptionist! Unbelievable!

In Scenario 1, "a receptionist" because I am describing her in a general context. She is a receptionist at a small business. Doesn't matter if there is only one receptionist at that firm, I am describing her general professional existence.

In Scenario 2, "the receptionist" because it's within a narrower context, within the business. She is the receptionist there (there is only one receptionist presumably). So if I use "a" here, I move away from that specific within-company context. So "the" is better.

Does this make sense (the explanations were provided by my English tutor)?