Write the brief before you speak to anyone
A single page is enough: the areas, the approximate size of each, the days and hours cleaning can occur, the frequency you have in mind, and anything unusual about access. Writing it forces you to decide what you actually want, which is harder than it sounds and is the step most buyers skip. It also means the three proposals answer the same question rather than three different ones.
Include what you are unsure about as well. If you do not know whether the carpets need periodic extraction or how often the windows should be done, say so and ask each provider to advise. Their answers become part of the comparison. A provider who recommends less than you expected, and explains why, is often more useful than one who agrees with everything in the brief.
