diff --git a/integrations/langgraph/python/ag_ui_langgraph/utils.py b/integrations/langgraph/python/ag_ui_langgraph/utils.py
index e310fc67da..30a0af7a96 100644
--- a/integrations/langgraph/python/ag_ui_langgraph/utils.py
+++ b/integrations/langgraph/python/ag_ui_langgraph/utils.py
@@ -404,6 +404,9 @@ def agui_messages_to_langchain(messages: List[AGUIMessage]) -> List[BaseMessage]
                 id=message.id,
                 content=message.content,
                 tool_call_id=message.tool_call_id,
+                # Carry the AG-UI failure signal onto LangChain's tool-result status, so a
+                # client-reported tool failure is not delivered to the model as a success.
+                status="error" if message.error else "success",
             ))
         else:
             raise ValueError(f"Unsupported message role: {role}")
diff --git a/integrations/langgraph/python/tests/test_message_conversion.py b/integrations/langgraph/python/tests/test_message_conversion.py
index cc98bcd5e4..92a9b29f73 100644
--- a/integrations/langgraph/python/tests/test_message_conversion.py
+++ b/integrations/langgraph/python/tests/test_message_conversion.py
@@ -82,6 +82,22 @@ def test_tool_message(self):
         assert isinstance(result[0], ToolMessage)
         assert result[0].content == "42"
         assert result[0].tool_call_id == "tc1"
+        # A tool result with no error maps to LangChain's default "success" status.
+        assert result[0].status == "success"
+
+    def test_tool_message_error_maps_to_status(self):
+        # A client-reported tool failure must reach the model as an error, not a
+        # silent success -- AG-UI's ToolMessage.error becomes status="error".
+        msg = AGUIToolMessage(
+            id="t1",
+            role="tool",
+            content="Tool failed: invalid id",
+            tool_call_id="tc1",
+            error="invalid id",
+        )
+        result = agui_messages_to_langchain([msg])
+        assert isinstance(result[0], ToolMessage)
+        assert result[0].status == "error"
 
     def test_multimodal_with_url(self):
         msg = AGUIUserMessage(
diff --git a/integrations/langgraph/typescript/src/message-conversion.test.ts b/integrations/langgraph/typescript/src/message-conversion.test.ts
index 8aed2935d8..f040b2ff23 100644
--- a/integrations/langgraph/typescript/src/message-conversion.test.ts
+++ b/integrations/langgraph/typescript/src/message-conversion.test.ts
@@ -78,6 +78,23 @@ describe("Message Conversion - All Types", () => {
       expect(result[0].type).toBe("tool");
       expect(result[0].content).toBe("42");
       expect(result[0].tool_call_id).toBe("tc1");
+      // A tool result with no error maps to LangChain's default "success" status.
+      expect(result[0].status).toBe("success");
+    });
+
+    it("should map a tool message error onto LangChain's status flag", () => {
+      // A client-reported tool failure must reach the model as an error, not a
+      // silent success — AG-UI's ToolMessage.error becomes status: "error".
+      const msg: Message = {
+        id: "t1",
+        role: "tool",
+        content: "Tool failed: invalid id",
+        toolCallId: "tc1",
+        error: "invalid id",
+      };
+      const result: any[] = aguiMessagesToLangChain([msg]);
+      expect(result[0].type).toBe("tool");
+      expect(result[0].status).toBe("error");
     });
 
     it("should throw for unsupported role", () => {
diff --git a/integrations/langgraph/typescript/src/utils.ts b/integrations/langgraph/typescript/src/utils.ts
index 54b66649dd..3d05a481fc 100644
--- a/integrations/langgraph/typescript/src/utils.ts
+++ b/integrations/langgraph/typescript/src/utils.ts
@@ -435,6 +435,9 @@ export function aguiMessagesToLangChain(messages: Message[]): LangGraphMessage[]
           type: message.role,
           tool_call_id: message.toolCallId,
           id: message.id,
+          // Carry the AG-UI failure signal onto LangChain's tool-result status, so a
+          // client-reported tool failure is not delivered to the model as a success.
+          status: message.error ? "error" : "success",
         } as LangGraphMessage);
         break;
       default: