I started a job as a mechanic in April of 2017. Over the course of last year I bought tools totaling at least $8000 that were required for my job. How do I report these?

Yes, you can claim the entire amount of the tools if they were purchased for a job you held when you purchased them. 

If you had your own business that used the tools, you could write off the full cost, but as an employee there are rules. 

The tools will be considered a job-related expense.  

Unfortunately, It is very difficult to qualify for the job-related expenses deduction. That's because the expense limit is so high. In order to qualify, your job-related expenses must be more than 2% of your AGI (adjusted gross income).

Also, job-related expenses are an itemized deductions.  Itemized deductions are items deductions added together from your personal tax records such as mortgage interest, charitable contribution, medical expense, etc.

If you cannot itemize, then you will not be able to deduct any part of the expense. 

So it will be listed under expenses and not assets?

Yes for an employee.  Assets if you owned a business.