isherwood is correct. Some so called roofers don't normally inspect anything under the sheathing. A Roofer is not a carpenter by definition. But then they are not being asked to build a wall or staircase now are they? A Roofer makes all decisions as to the structure of a roof. That means a Roofer works on, makes decisions on structure, load bearings, ventilation, truss or rafters, sofettes and anything related to the structure of the roof which is from the attic ceiling joists up to the ridge line.
isherwood may be referring to so called Shinglers working under the guise as a Roofer. These are Roofers that only want to work on replacing a piece of sheathing and laying shingles. Commonly known as shinglers. All they do is essentially remove and replace from the underlayment up. Sadly this is common practice amongst roofing contractors. And not what most home owners need when it comes to roof inspection and repair.
You have to be wary of Roofing contractors that are actually just Shinglers that will claim they will make all repairs, then when the roof is opened up, they don't actually fix anything but rather just cover the damage over with sheathing and shingles.
A true to the term Roofer will indeed do a full inspection of the roof structure, and walk the roof itself to look for damage, roof structure integrity, inadequacies in ventilation, code violations and so and discuss all their findings with the homeowner so the homeowner can make a informed decision when it comes to repairs.
Another option is to hirer an independent licensed roofer/roof inspector with experience in roofing and up to date on building codes to do a full roof inspection. This is a person that doesn't work for a contractor and is not trying to sell you a roof. You have to be equally as careful as to who you hire as not all independent inspectors are the same. You want one that specializes in roof inspections. Not just general building inspections.
Equally you can get three licensed bonified Roofers to inspect and give detailed bids as to the work you want done, which you should do anyway.
Never sign anything that gives them the authority to negotiate with the insurance company - it's illegal. You wouldn't be in trouble, they would. It's felony in most states.
Never sign anything that states they are to receive all monies before they start work. Or all claim money goes to them. Known as an AOB these can be worded differently. It's not illegal, but very commonly used in scams. It means all claim money they get, including for any other damages to the property included in the claim. You more than likely will end up with a subpar roof if any at all, and find it very difficult to get claim monies over and above the repair cost returned once they have it. They know push come to shove, you'll have to sue them to get it back.