Yes, if you work as an employee, and you itemize, you can deduct the expense for tools on Line 22 of Schedule A, as an unreimbursed job expense, miscellaneous deduction.
On Schedule A, the deduction is subject to the 2% limit rule. You can claim the amount of expenses that are more than 2% of your adjusted gross income (line 37, form 1040)
---See IRS Publication 17, page 190.
If you are a self employed mechanic, you can deduct the expense for tools on your Schedule C. The 2% rule does not apply if you are self employed and reporting on Schedule C.
Most tools depreciate over time and have an expected lifespan of several years, so your correct entry on your return would be the the depreciated value of your tools.
The easiest way is to figure depreciation is to estimate the lifespan of each individual tool, then divide the {cost of the item new} less the {salvage value} by the [number of years] in it's estimated lifespan.
(Cost new - Salvage value) divided by (number of years) = yearly depreciation value.
Then you should deduct the same amount of depreciation each year on your taxes for the life of the tool.
You should attach a list of your tools to your tax return showing each individual tool, the date it was purchased, the original value, the date it was placed in service, number of years in the lifespan of the tool, the amount of depreciation per year, and the current depreciation value for 2006. Add the last column, and enter the total depreciated value for 2006 on Schedule A, or Schedule C.
The cost of small tools and supplies that you bought in 2006, needed for your job, for which you do not receive any reimbursement, that have a life span of 1 year or less, can be entered at full value on your attached list and included in the total at full value.
--IRS Publication17, page 190
Use IRS Publication 946, for information on depreciation.