diff --git a/client/src/components/AppsTab.tsx b/client/src/components/AppsTab.tsx
index 2b6d75358..8df67e305 100644
--- a/client/src/components/AppsTab.tsx
+++ b/client/src/components/AppsTab.tsx
@@ -127,9 +127,29 @@ const AppsTab = ({
   }, []);
 
   // Function to check if any form has validation errors
+  const validateJsonParams = useCallback(() => {
+    const validatedParams = { ...params };
+    let hasErrors = false;
+
+    for (const [key, ref] of Object.entries(formRefs.current)) {
+      if (!ref) continue;
+
+      const result = ref.validateJson();
+      if (!result.isValid) {
+        hasErrors = true;
+      } else if (result.value !== undefined) {
+        validatedParams[key] = result.value;
+      }
+    }
+
+    setHasValidationErrors(hasErrors);
+    if (!hasErrors) setParams(validatedParams);
+    return { hasErrors, validatedParams };
+  }, [params]);
+
   const checkValidationErrors = useCallback(() => {
     const errors = Object.values(formRefs.current).some(
-      (ref) => ref && !ref.validateJson().isValid,
+      (ref) => ref && ref.hasJsonError(),
     );
     setHasValidationErrors(errors);
     return errors;
@@ -249,12 +269,15 @@ const AppsTab = ({
   }, []);
 
   const handleOpenApp = useCallback(async () => {
-    if (!selectedTool || checkValidationErrors()) {
+    if (!selectedTool) {
       return;
     }
 
-    await executeToolAndOpenApp(selectedTool, params);
-  }, [checkValidationErrors, executeToolAndOpenApp, params, selectedTool]);
+    const { hasErrors, validatedParams } = validateJsonParams();
+    if (hasErrors) return;
+
+    await executeToolAndOpenApp(selectedTool, validatedParams);
+  }, [executeToolAndOpenApp, selectedTool, validateJsonParams]);
 
   const handleSelectTool = useCallback(
     (tool: Tool) => {
diff --git a/client/src/components/DynamicJsonForm.tsx b/client/src/components/DynamicJsonForm.tsx
index ba1cc73f9..34e85cd70 100644
--- a/client/src/components/DynamicJsonForm.tsx
+++ b/client/src/components/DynamicJsonForm.tsx
@@ -27,7 +27,11 @@ interface DynamicJsonFormProps {
 }
 
 export interface DynamicJsonFormRef {
-  validateJson: () => { isValid: boolean; error: string | null };
+  validateJson: () => {
+    isValid: boolean;
+    error: string | null;
+    value?: JsonValue;
+  };
   hasJsonError: () => boolean;
 }
 
@@ -245,10 +249,10 @@ const DynamicJsonForm = forwardRef<DynamicJsonFormRef, DynamicJsonFormProps>(
     };
 
     const validateJson = () => {
-      if (!isJsonMode) return { isValid: true, error: null };
+      if (!isJsonMode) return { isValid: true, error: null, value };
       try {
         const jsonStr = rawJsonValue?.trim();
-        if (!jsonStr) return { isValid: true, error: null };
+        if (!jsonStr) return { isValid: true, error: null, value };
         const parsed = JSON.parse(jsonStr);
         // Clear any pending debounced update and immediately update parent
         if (timeoutRef.current) {
@@ -256,7 +260,7 @@ const DynamicJsonForm = forwardRef<DynamicJsonFormRef, DynamicJsonFormProps>(
         }
         onChange(parsed);
         setJsonError(undefined);
-        return { isValid: true, error: null };
+        return { isValid: true, error: null, value: parsed };
       } catch (err) {
         const errorMessage =
           err instanceof Error ? err.message : "Invalid JSON";
diff --git a/client/src/components/ToolsTab.tsx b/client/src/components/ToolsTab.tsx
index 15b85fd67..cc92f81ca 100644
--- a/client/src/components/ToolsTab.tsx
+++ b/client/src/components/ToolsTab.tsx
@@ -224,6 +224,26 @@ const ToolsTab = ({
     return errors;
   };
 
+  const validateJsonParams = () => {
+    const validatedParams = { ...params };
+    let hasErrors = false;
+
+    for (const [key, ref] of Object.entries(formRefs.current)) {
+      if (!ref) continue;
+
+      const result = ref.validateJson();
+      if (!result.isValid) {
+        hasErrors = true;
+      } else if (result.value !== undefined) {
+        validatedParams[key] = result.value;
+      }
+    }
+
+    setHasValidationErrors(hasErrors);
+    if (!hasErrors) setParams(validatedParams);
+    return { hasErrors, validatedParams };
+  };
+
   useEffect(() => {
     const params = Object.entries(
       selectedTool?.inputSchema.properties ?? [],
@@ -808,7 +828,8 @@ const ToolsTab = ({
                 <Button
                   onClick={async () => {
                     // Validate JSON inputs before calling tool
-                    if (checkValidationErrors(true)) return;
+                    const { hasErrors, validatedParams } = validateJsonParams();
+                    if (hasErrors) return;
 
                     try {
                       setIsToolRunning(true);
@@ -828,7 +849,7 @@ const ToolsTab = ({
                       }, {});
                       await callTool(
                         selectedTool.name,
-                        params,
+                        validatedParams,
                         Object.keys(metadata).length ? metadata : undefined,
                         runAsTask,
                       );
diff --git a/client/src/components/__tests__/AppsTab.test.tsx b/client/src/components/__tests__/AppsTab.test.tsx
index 315a95ccf..c76c00a0a 100644
--- a/client/src/components/__tests__/AppsTab.test.tsx
+++ b/client/src/components/__tests__/AppsTab.test.tsx
@@ -662,6 +662,39 @@ describe("AppsTab", () => {
     expect(toolInput.query).toBe("first value");
   });
 
+  it("should open an app with the latest JSON value", async () => {
+    const jsonApp: Tool = {
+      name: "jsonApp",
+      inputSchema: {
+        type: "object",
+        properties: {
+          config: { type: "object", additionalProperties: true },
+        },
+      },
+      _meta: { ui: { resourceUri: "ui://json" } },
+    } as Tool & { _meta?: { ui?: { resourceUri?: string } } };
+    const mockCallTool = jest.fn(
+      async () =>
+        ({
+          content: [{ type: "text", text: "done" }],
+        }) as CompatibilityCallToolResult,
+    );
+
+    renderAppsTab({ tools: [jsonApp], callTool: mockCallTool });
+
+    fireEvent.click(screen.getByText("jsonApp"));
+    fireEvent.change(screen.getByRole("textbox"), {
+      target: { value: '{"key":"updated"}' },
+    });
+    fireEvent.click(screen.getByRole("button", { name: /open app/i }));
+
+    await waitFor(() => {
+      expect(mockCallTool).toHaveBeenCalledWith("jsonApp", {
+        config: { key: "updated" },
+      });
+    });
+  });
+
   it("should keep input view when opening fails and recover button state", async () => {
     const toolWithFields: Tool = {
       name: "failingApp",
diff --git a/client/src/components/__tests__/ToolsTab.test.tsx b/client/src/components/__tests__/ToolsTab.test.tsx
index 5678914d6..d266b39f9 100644
--- a/client/src/components/__tests__/ToolsTab.test.tsx
+++ b/client/src/components/__tests__/ToolsTab.test.tsx
@@ -909,6 +909,34 @@ describe("ToolsTab", () => {
     });
   });
 
+  it("should submit the latest JSON value without waiting for the debounce", async () => {
+    const jsonTool: Tool = {
+      name: "jsonTool",
+      inputSchema: {
+        type: "object",
+        properties: {
+          config: { type: "object", additionalProperties: true },
+        },
+      },
+    };
+    const callToolMock = jest.fn(async () => {});
+
+    renderToolsTab({ selectedTool: jsonTool, callTool: callToolMock });
+
+    fireEvent.change(screen.getByRole("textbox"), {
+      target: { value: '{"key":"updated"}' },
+    });
+    fireEvent.click(screen.getByRole("button", { name: /run tool/i }));
+
+    await act(async () => {});
+    expect(callToolMock).toHaveBeenCalledWith(
+      "jsonTool",
+      { config: { key: "updated" } },
+      undefined,
+      false,
+    );
+  });
+
   describe("Reserved metadata keys", () => {
     test.each`
       description                             | value                             | message