Single or multiple form field(s)

Consider an application where a user can make a list of people to meet during the day, and share that with a colleague/secretary/etc. It is something between a todo list and an actual calendar.

So when the user clicks a plus/add button, a modal shows up with a simple form with a couple of fields and a button. In the form the user can enter information about an appointment.

For designing this form, I am trying to decide between

• A. whether to make this a multi field form, so they have to specify 1) who the meeting is with 2) what time it is 3) where it will be held, 4) topic of the meeting 5) comments, and maybe another 1-2 fields.
• B. just make it a very simple 1-2 field form. The user can just type out whatever they want in a single field and an optional comments field and touch the button.

In the first approach, it is all very structured. This prompts the user to break down the information into specific fields. This works well for appointments where everything is decided in advance.

In many cases however the actual information may not be as clear. For instance, I am thinking of having a meeting with either X or Y (from team Z) either after lunch or before leaving the office, and the place isn't decided - either I drop by their desk or they come by my desk and maybe we go to the coffee machine or snack bar. Before actual usage, this is believed to be the more likely use case.

Putting all this ^ vagueness into a form with fixed fields can be cumbersome and places a cognitive load on the user. So is it maybe better to make the form very simplistic and let the users decide how they want to fill in the information?

So it is like the unit of activity can be considered to be either the individual appointments themselves, or more like a todo list/guide for the user.

What do the experienced designers think? How should I decide which approach might be better?