Pilot speaking with a mech eng background.
The only way your going to be able to stop it is by proving that the use of low quality tools is going to cost more than using high quality ones.
You a bit stuffed as they write the capital cost off over 3 years I think for hand tools in relation to tax. So to you they are still worth xxx amount to the accountant they are worth zero.
You will hit the problem though that if you state it will cost xxxxx amount if the tool breaks they will say you can keep x amount in stock.
The high quality tools for individuals buy themselves is an investment but in accountancy terms its not as the say that they will never see that investment returned in their 3 year capital plan.
The best I succeeded in doing was to get medium quality tools provided and an option for an allowance to self purchase and recover the VAT back to the technician through the company which worked quite well although I suspect it was technically illegal for the VAT recovery. After 3 years the tool was thier's to remove. Specialist tools were company bought.