Notice from the consumer (1005.11(b)) requires that the bank be able to identify the customer and account and why they believe an error has happened. It could be the person’s name and account number, but
they could have a unique name that clearly identifies them or a SSAN as an example. If the person says $100 was taken the bank should quickly review transactions. If there is one debit in that amount that may well be it. If there are multiple $100 transfers, or multiple transfers that could total $100 then it is not clear. In your example, if there is one Amazon charge on the account that would identify it. If there are many and the customer has a history of charges there, I would say clarification is needed. In that event I would say the bank has not been notified correctly as there is no expectation that every single or series of debits totaling the claim amount or to Amazon, be investigated.
In that case attempts should be made to call, email, text, contact via internet banking or snail mail the customer for clarification. Document your efforts and why the description was considered insufficient.