Starting in 2018, employees (W-2 recipients) are no longer able to deduct any job expenses, including tools.
Even in the "old days" , job expenses were only a misc. itemized deduction. You only got to deduct that portion of your misc. itemized deductions that exceeded 2% of your AGI, and then only if your total itemized deductions exceeded the standard deduction (which was doubled under the 2018 tax law. . (2% rule explained: https://ttlc.intuit.com/questions/2902781-what-is-the-2-rule ).
Self employed mechanics can still deduct tools, except those that must be depreciated*, on Schedule C. The deduction is not subject to either the 2% rule or itemizing.
There's always more risk of an audit with bigger expenses. The risk is small and easily supported with receipts.
*https://www.hrblock.com/tax-center/filing/adjustments-and-deductions/are-work-clothes-and-tools-tax-...
https://www.thebalance.com/a-beginner-s-guide-to-section-179-deductions-5218624
