CODE EXAMPLE FOR PHP

How to programmatically grab the product description in WooCommerce?

2) From the WC_Product Object using set_description() method
// Get the WC_Product Object instance (optional if needed)
$product = wc_get_product( $product_id );

// Set the description
$product->set_description('This is the <strong>product description</strong> content.');

$product->save(); // Save product data