You do not need to know the square footage down to the inch. But a clear description helps a cleaner understand what you want done and whether the job needs an on-site look.
Start with the surface and location
Say whether the work is a driveway, pavers, fence, house exterior, boat, vehicle or commercial area. Include the property address or neighborhood so the cleaner can confirm they serve that location. If the job has multiple surfaces, list each separately.
Send photos that answer questions
A wide photo shows the whole area. A closer photo shows spots, buildup, joints, paint or anything you are worried about. If there are obstacles, tight access or nearby landscaping, show those too. Photos are useful for a first conversation; they do not always replace an in-person assessment.
Point out the material
Concrete, pavers, siding, wood and vehicle finishes are not interchangeable. If you know the material, mention it. If not, say so and share a close photo. Do not assume that the highest-pressure method is right for every surface.
Ask what is included
Before accepting a quote, make sure both sides understand the specific area, any stain or spot treatment, moveable objects, water access, scheduling and how a change in scope would be handled. If you are comparing quotes, compare the same work—not just the total.
What about timing?
If you have a deadline, share it up front. The cleaner can then tell you whether the schedule is realistic. Same-day work may be possible on some days, but should be confirmed rather than assumed.