diff --git a/api/core/workflow/nodes/tool/tool_node.py b/api/core/workflow/nodes/tool/tool_node.py
index b0bc1246bd..bfa7db3943 100644
--- a/api/core/workflow/nodes/tool/tool_node.py
+++ b/api/core/workflow/nodes/tool/tool_node.py
@@ -137,4 +137,8 @@ class ToolNode(BaseNode):
         """
         Extract variable selector to variable mapping
         """
-        pass
\ No newline at end of file
+        return {
+            k.value_selector: k.variable
+            for k in cast(ToolNodeData, node_data).tool_parameters
+            if k.variable_type == 'selector'
+        }
\ No newline at end of file