Short answer:
1. replace the timing belt, pulleys, and tensioner
2. if a proper job isn't tolerable for some reason - then replace the timing belt and the lower cogged pulley.
Long answer:
Are you concerned with a warranty of 12 month/12,000 miles (shop warranty after the repair) or another 100,000 reliable miles?
Replace the belt, tensioner, and pulleys almost as a rule. I will occasionally "inspect" each part individually on a case by case basis. The problem with "inspecting" parts is that the "inspection" is tilted and tainted by the existing timing belt ideas and approach (which at many shops is low grade "belt only") and unlikely to reflect the failure modes and rates of given parts for the next 100,000 miles.
Case in point - at the very minimum one should replace the belt and the lower cogged idler. That is by far the most common pulley to fail and should be replaced every time. If it fails then a $40 pulley causes $2000+ in engine damage via bent valves. If any average consumer knew this I find it hard to believe they would not replace the single highest failure rate item for $40 or less. You can literally google this and see zillions of youtube videos and photos I'm sure of it, because it's very common.
It is true the tensioner, if properly compressed for reuse (a major issue is the compressing/reuse process itself, not just the pulley/miles), then the tensioners are fairly reliable 200,000 miles components. But here again for the cost of a timing belt kit it's just not worth it. I guess you're on the hook for local dealer pricing so that's going to sway your decision and largely the reason they don't do the job right, it's not their fault they just have difficult decisions to make dealing with the public. They don't want to quote $1,000 timing belt prices when the guy down the street charges $300. And in general consumers aren't equipped or digest well when you try to explain to them the differences and realities, they just want it done and they dont' want to pay a ton. I'm not charging any labor, make no money, so the cost is already low but i often get lost/confused looks trying to explain anything technical. So I just try to ask if $XYZ is okay for me to do this right. Dealers have a much harder time communicating that, the differences, and options, and have to make hard judgement calls and mostly one-size-fits-all service approaches on the services they offer based on their current reality. That's not easy.