diff --git a/src/HttpAsyncClient.php b/src/HttpAsyncClient.php
index 592fd49..492e511 100644
--- a/src/HttpAsyncClient.php
+++ b/src/HttpAsyncClient.php
@@ -19,7 +19,7 @@ interface HttpAsyncClient
      *
      * @param RequestInterface $request
      *
-     * @return Promise
+     * @return Promise Resolves a PSR-7 Response or fails with an Http\Client\Exception.
      *
      * @throws \Exception If processing the request is impossible (eg. bad configuration).
      */