diff --git a/lib/is_external_link.js b/lib/is_external_link.js
index f07012f3..86eeec70 100644
--- a/lib/is_external_link.js
+++ b/lib/is_external_link.js
@@ -8,6 +8,8 @@ const cache = new Cache();
 /**
  * Check whether the link is external
  * @param {String} input The url to check
+ * @param {String} input The hostname / url of website
+ * @param {Array} input Exclude hostnames. Specific subdomain is required when applicable, including www.
  * @returns {Boolean} True if the link doesn't have protocol or link has same host with config.url
  */