Is it TOC? and / or test of details?

It could be either, for example:

1 Substantive. If the invoices are o/s they will contribute to receivables and the above would help us to decide that they were genuine etc.

2 ToC. No controls have been mentioned in your example, but the above could be used as part-evidence that the some of the controls in place over invoicing were operating effectively. After all, if you found errors in this test it would mean that there was something wrong in the internal control system.

lets say if the clerk carries out the above procedure to ensure that correct amounts are charged and entered in to the payables ledger..
so if i were to perform test of control then i would just re-perform the test right?

and if carried out as a substantive test, this test confirms invoice accuracy and completeness of liabilities.. because if the amounts on invoice are incorrect ultimately liabilities are going to be under/over stated..

so is the above reasoning correct?

That's right.

The big problem in practice is testing that a control has been performed if there is no evidence of it having been performed. For example, if the clerk does not initial the documents showing that the work has been done, how do you know it has been done - there's no evidence of the control. So, as well as reperformance you would also need to use observation and enquiry, and look for evidence of corrections made.