diff --git a/src/Capability/Registry/ElementReference.php b/src/Capability/Registry/ElementReference.php
index a49b2eb3..6df359a0 100644
--- a/src/Capability/Registry/ElementReference.php
+++ b/src/Capability/Registry/ElementReference.php
@@ -12,7 +12,7 @@
 namespace Mcp\Capability\Registry;
 
 /**
- * @phpstan-type Handler \Closure|array{0: object|string, 1: string}|string
+ * @phpstan-type Handler (\Closure(mixed...): mixed)|array{0: object|string, 1: string}|string
  *
  * @author Kyrian Obikwelu <koshnawaza@gmail.com>
  */