WordPress at a glance
filter is not described

the_content filter-hook . WC 1.0

Usage

add_filter( 'the_content', 'filter_function_name_2903' );
function filter_function_name_2903( $product_description ){
	// filter...

	return $product_description;
}
$product_description
-

Where the hook is called

WC_API_Products::get_product_data()
the_content
woocommerce/includes/legacy/api/v1/class-wc-api-products.php 325
'description'        => apply_filters( 'the_content', $product->get_description() ),
woocommerce/includes/legacy/api/v1/class-wc-api-products.php 342
'purchase_note'      => apply_filters( 'the_content', $product->get_purchase_note() ),

Where in WP core the hook is used WooCommerce

woocommerce/includes/class-wc-template-loader.php 241
add_filter( 'the_content', array( __CLASS__, 'unsupported_theme_shop_content_filter' ), 10 );
woocommerce/includes/class-wc-template-loader.php 252
add_filter( 'the_content', array( __CLASS__, 'unsupported_theme_product_content_filter' ), 10 );
woocommerce/includes/class-wc-template-loader.php 467
remove_filter( 'the_content', array( __CLASS__, 'unsupported_theme_shop_content_filter' ) );
woocommerce/includes/class-wc-template-loader.php 522
remove_filter( 'the_content', array( __CLASS__, 'unsupported_theme_product_content_filter' ) );