You do need to lock your tools away to a reasonable degree to be covered by your insurance. If you concentrate all of the security on the shed door though they may resort to removing a window or lifting the roof of a regular garden shed. If you are over thirtyish you could put a sound bomb in the shed or back of the van. These are similar and sometimes the same as the high-pitched heron/cat deterrent devices. They are unbearable to the young intruders (U25) but bearable to 'older' ears. A shed solar-powered shed alarm is also a good move for both sheds and vans if they are close enough for you to hear it. Smartwater is one way of marking the item along with UV pens. They are both removable with Isopropanol or Acetone but thieves rarely go to the trouble of even trying to remove them. Generally, they need to get them sold straight away to get their drug money so don't over-think their intelligence over their desperation. If using a UV pen then set a reminder on your calendar to refresh the markings. These should be postcode and house number minimum. Keep your precious hand tools separate from the electronic stuff. They are rarely interested in your planes and chisels. They sometimes end up taking them because they are in the same box as the circular saws and drills. They won't get much if anything from the type of person that deals in stolen tools. Police often recover tools in raids and use UV to look for markings so don't hide them too well. If you put a nice large X in a prominent location it will show up to the Officer drawing their attention and prompting them to have a closer look at the item. The reason many tools end up at the auctions is because the insurance has been paid out so the owner may not want them back because they will have not only replaced the tool/s but they would have to return the insurance money - as I understand it.