Korean skincare sample shipment to Germany, what documents do brands usually prepare?

Hi, we are currently reviewing several Korean skincare brands for the German market. Before placing any trial orders, we usually request samples for product evaluation. However, we noticed that the documents provided for sample shipments can vary depending on the brand. For Korean brands that have shipped cosmetic samples to Germany before, what documents do you normally prepare together with the shipment? - Proforma invoice or commercial invoice, INCI list, product information sheet? Any other documents requested by courier companies or customs? We would like to make sure the sample evaluation process goes smoothly before moving forward with potential distribution. Any experience from Korean brands or European buyers would be appreciated.