"As a [role] I want to [action] so that I get [result]."

This is a simple, unambiguous sentence structure for requirements that is used in Agile development methodologies like SCRUM.

I recommend it because, with this structure, a savvy coder can get their audience/users to draft the requirements themselves -- and there is no better way to stay on the same page and get it right than this way.

So once more:

"As a [role] I want to [action] so that I get [result]."