diff --git a/src/workflow/ArcanistCallConduitWorkflow.php b/src/workflow/ArcanistCallConduitWorkflow.php
--- a/src/workflow/ArcanistCallConduitWorkflow.php
+++ b/src/workflow/ArcanistCallConduitWorkflow.php
@@ -62,6 +62,8 @@
     }
     $method = reset($method);
 
+    $console = PhutilConsole::getConsole();
+    $console->writeOut("%s\n", pht('Waiting for JSON parameters on stdin...'));
     $params = @file_get_contents('php://stdin');
     $params = json_decode($params, true);
     if (!is_array($params)) {