WordPress at a glance
filter is not described

rest_index filter-hook . WP 4.4.0

Filters the API root index data.

This contains the data describing the API. This includes information about supported authentication schemes, supported namespaces, routes available on the API, and a small amount of data about the site.

Usage

add_filter( 'rest_index', 'filter_function_name_2220' );
function filter_function_name_2220( $response ){
	// filter...

	return $response;
}
$response(WP_REST_Response)
Response data.

Where the hook is called

WP_REST_Server::get_index()
rest_index
wp-includes/rest-api/class-wp-rest-server.php 1046
return apply_filters( 'rest_index', $response );

Where the hook is used (in WP core)

Does not used.