fix: add proactive tool rejection when dialog is open (#1978)

Adding proactive rejection of tool execution for tools which currently
get blocked due to open dialogs (related to #1069 )

src/McpPage.ts

@@ -81,6 +81,14 @@ export class McpPage implements ContextPage {
     this.#dialog = undefined;
   }
 
+  throwIfDialogOpen(): void {
+    if (this.#dialog) {
+      throw new Error(
+        `A dialog is open (${this.#dialog.type()}: ${this.#dialog.message()}).`,
+      );
+    }
+  }
+
   getInPageTools(): ToolGroup<ToolDefinition> | undefined {
     return this.inPageTools;
   }

src/index.ts

@@ -233,14 +233,17 @@ export async function createMcpServer(
 
           response.setRedactNetworkHeaders(serverArgs.redactNetworkHeaders);
           try {
+            const page =
+              serverArgs.experimentalPageIdRouting &&
+              params.pageId &&
+              !serverArgs.slim
+                ? context.getPageById(params.pageId)
+                : context.getSelectedMcpPage();
+            response.setPage(page);
+            if (tool.blockedByDialog) {
+              page.throwIfDialogOpen();
+            }
             if ('pageScoped' in tool && tool.pageScoped) {
-              const page =
-                serverArgs.experimentalPageIdRouting &&
-                params.pageId &&
-                !serverArgs.slim
-                  ? context.getPageById(params.pageId)
-                  : context.getSelectedMcpPage();
-              response.setPage(page);
               await tool.handler(
                 {
                   params,

src/tools/ToolDefinition.ts

@@ -46,6 +46,7 @@ export interface BaseToolDefinition<
     conditions?: string[];
   };
   schema: Schema;
+  blockedByDialog: boolean;
 }
 
 export interface ToolDefinition<
@@ -255,6 +256,7 @@ export type ContextPage = Readonly<{
 
   getDialog(): Dialog | undefined;
   clearDialog(): void;
+  throwIfDialogOpen(): void;
   waitForEventsAfterAction(
     action: () => Promise<unknown>,
     options?: {timeout?: number; handleDialog?: 'accept' | 'dismiss' | string},

src/tools/console.ts

@@ -78,6 +78,7 @@ export const listConsoleMessages = definePageTool(cliArgs => {
           'Set to true to return the preserved messages over the last 3 navigations.',
         ),
     },
+    blockedByDialog: false,
     handler: async (request, response) => {
       response.setIncludeConsoleData(true, {
         pageSize: request.params.pageSize,
@@ -103,6 +104,7 @@ export const getConsoleMessage = definePageTool({
         'The msgid of a console message on the page from the listed console messages',
       ),
   },
+  blockedByDialog: false,
   handler: async (request, response) => {
     response.attachConsoleMessage(request.params.msgid);
   },

src/tools/emulation.ts

@@ -66,6 +66,7 @@ export const emulate = definePageTool({
         `Emulate device viewports '<width>x<height>x<devicePixelRatio>[,mobile][,touch][,landscape]'. 'touch' and 'mobile' to emulate mobile devices. 'landscape' to emulate landscape mode.`,
       ),
   },
+  blockedByDialog: true,
   handler: async (request, _response, context) => {
     const page = request.page;
     await context.emulate(request.params, page.pptrPage);

src/tools/extensions.ts

@@ -21,6 +21,7 @@ export const installExtension = defineTool({
       .string()
       .describe('Absolute path to the unpacked extension folder.'),
   },
+  blockedByDialog: false,
   handler: async (request, response, context) => {
     const {path} = request.params;
     const id = await context.installExtension(path);
@@ -38,6 +39,7 @@ export const uninstallExtension = defineTool({
   schema: {
     id: zod.string().describe('ID of the extension to uninstall.'),
   },
+  blockedByDialog: false,
   handler: async (request, response, context) => {
     const {id} = request.params;
     await context.uninstallExtension(id);
@@ -54,6 +56,7 @@ export const listExtensions = defineTool({
     readOnlyHint: true,
   },
   schema: {},
+  blockedByDialog: false,
   handler: async (_request, response, _context) => {
     response.setListExtensions();
   },
@@ -69,6 +72,7 @@ export const reloadExtension = defineTool({
   schema: {
     id: zod.string().describe('ID of the extension to reload.'),
   },
+  blockedByDialog: false,
   handler: async (request, response, context) => {
     const {id} = request.params;
     const extension = await context.getExtension(id);
@@ -90,6 +94,7 @@ export const triggerExtensionAction = defineTool({
   schema: {
     id: zod.string().describe('ID of the extension to trigger the action for.'),
   },
+  blockedByDialog: false,
   handler: async (request, response, context) => {
     const {id} = request.params;
     await context.triggerExtensionAction(id);

src/tools/inPage.ts

@@ -51,6 +51,7 @@ export const listInPageTools = definePageTool({
     conditions: ['inPageTools'],
   },
   schema: {},
+  blockedByDialog: false,
   handler: async (_request, response, _context) => {
     response.setListInPageTools();
   },
@@ -71,6 +72,7 @@ export const executeInPageTool = definePageTool({
       .optional()
       .describe('The JSON-stringified parameters to pass to the tool'),
   },
+  blockedByDialog: false,
   handler: async (request, response) => {
     const toolName = request.params.toolName;
     let params: Record<string, unknown> = {};

src/tools/input.ts

@@ -58,6 +58,7 @@ export const click = definePageTool({
     dblClick: dblClickSchema,
     includeSnapshot: includeSnapshotSchema,
   },
+  blockedByDialog: true,
   handler: async (request, response) => {
     const uid = request.params.uid;
     const handle = await request.page.getElementByUid(uid);
@@ -97,6 +98,7 @@ export const clickAt = definePageTool({
     dblClick: dblClickSchema,
     includeSnapshot: includeSnapshotSchema,
   },
+  blockedByDialog: true,
   handler: async (request, response) => {
     const page = request.page;
     await page.waitForEventsAfterAction(async () => {
@@ -130,6 +132,7 @@ export const hover = definePageTool({
       ),
     includeSnapshot: includeSnapshotSchema,
   },
+  blockedByDialog: true,
   handler: async (request, response) => {
     const uid = request.params.uid;
     const handle = await request.page.getElementByUid(uid);
@@ -233,6 +236,7 @@ export const fill = definePageTool({
     value: zod.string().describe('The value to fill in'),
     includeSnapshot: includeSnapshotSchema,
   },
+  blockedByDialog: true,
   handler: async (request, response, context) => {
     const page = request.page;
     await page.waitForEventsAfterAction(async () => {
@@ -261,6 +265,7 @@ export const typeText = definePageTool({
     text: zod.string().describe('The text to type'),
     submitKey: submitKeySchema,
   },
+  blockedByDialog: true,
   handler: async (request, response) => {
     const page = request.page;
     await page.waitForEventsAfterAction(async () => {
@@ -289,6 +294,7 @@ export const drag = definePageTool({
     to_uid: zod.string().describe('The uid of the element to drop into'),
     includeSnapshot: includeSnapshotSchema,
   },
+  blockedByDialog: true,
   handler: async (request, response) => {
     const fromHandle = await request.page.getElementByUid(
       request.params.from_uid,
@@ -330,6 +336,7 @@ export const fillForm = definePageTool({
       .describe('Elements from snapshot to fill out.'),
     includeSnapshot: includeSnapshotSchema,
   },
+  blockedByDialog: true,
   handler: async (request, response, context) => {
     const page = request.page;
     for (const element of request.params.elements) {
@@ -365,6 +372,7 @@ export const uploadFile = definePageTool({
     filePath: zod.string().describe('The local path of the file to upload'),
     includeSnapshot: includeSnapshotSchema,
   },
+  blockedByDialog: true,
   handler: async (request, response, context) => {
     const {uid, filePath} = request.params;
     context.validatePath(filePath);
@@ -415,6 +423,7 @@ export const pressKey = definePageTool({
       ),
     includeSnapshot: includeSnapshotSchema,
   },
+  blockedByDialog: true,
   handler: async (request, response) => {
     const page = request.page;
     const tokens = parseKey(request.params.key);

src/tools/lighthouse.ts

@@ -43,6 +43,7 @@ export const lighthouseAudit = definePageTool({
       .optional()
       .describe('Directory for reports. If omitted, uses temporary files.'),
   },
+  blockedByDialog: true,
   handler: async (request, response, context) => {
     const page = request.page;
     const categories = ['accessibility', 'seo', 'best-practices'];

src/tools/memory.ts

@@ -22,6 +22,7 @@ export const takeMemorySnapshot = definePageTool({
       .string()
       .describe('A path to a .heapsnapshot file to save the heapsnapshot to.'),
   },
+  blockedByDialog: true,
   handler: async (request, response, context) => {
     const page = request.page;
     context.validatePath(request.params.filePath);
@@ -48,6 +49,7 @@ export const exploreMemorySnapshot = defineTool({
   schema: {
     filePath: zod.string().describe('A path to a .heapsnapshot file to read.'),
   },
+  blockedByDialog: false,
   handler: async (request, response, context) => {
     context.validatePath(request.params.filePath);
     const stats = await context.getHeapSnapshotStats(request.params.filePath);
@@ -79,6 +81,7 @@ export const getMemorySnapshotDetails = defineTool({
       .optional()
       .describe('The page size for pagination of aggregates.'),
   },
+  blockedByDialog: false,
   handler: async (request, response, context) => {
     context.validatePath(request.params.filePath);
     const aggregates = await context.getHeapSnapshotAggregates(
@@ -111,6 +114,7 @@ export const getNodesByClass = defineTool({
     pageIdx: zod.number().optional().describe('The page index for pagination.'),
     pageSize: zod.number().optional().describe('The page size for pagination.'),
   },
+  blockedByDialog: false,
   handler: async (request, response, context) => {
     context.validatePath(request.params.filePath);
     const nodes = await context.getHeapSnapshotNodesByUid(

src/tools/network.ts

@@ -70,6 +70,7 @@ export const listNetworkRequests = definePageTool({
         'Set to true to return the preserved requests over the last 3 navigations.',
       ),
   },
+  blockedByDialog: false,
   handler: async (request, response, context) => {
     const data = await request.page.getDevToolsData();
     response.attachDevToolsData(data);
@@ -113,6 +114,7 @@ export const getNetworkRequest = definePageTool({
         'The absolute or relative path to a .network-response file to save the response body to. If omitted, the body is returned inline.',
       ),
   },
+  blockedByDialog: true,
   handler: async (request, response, context) => {
     context.validatePath(request.params.requestFilePath);
     context.validatePath(request.params.responseFilePath);

src/tools/pages.ts

@@ -84,6 +84,7 @@ export const listPages = defineTool(args => {
       readOnlyHint: true,
     },
     schema: {},
+    blockedByDialog: false,
     handler: async (_request, response) => {
       response.setIncludePages(true);
       response.setListInPageTools();
@@ -110,6 +111,7 @@ export const selectPage = defineTool({
       .optional()
       .describe('Whether to focus the page and bring it to the top.'),
   },
+  blockedByDialog: false,
   handler: async (request, response, context) => {
     const page = context.getPageById(request.params.pageId);
     context.selectPage(page);
@@ -134,6 +136,7 @@ export const closePage = defineTool({
       .number()
       .describe('The ID of the page to close. Call list_pages to list pages.'),
   },
+  blockedByDialog: false,
   handler: async (request, response, context) => {
     try {
       await context.closePage(request.params.pageId);
@@ -185,6 +188,7 @@ export const newPage = defineTool(args => {
         : {}),
       ...timeoutSchema,
     },
+    blockedByDialog: false,
     handler: async (request, response, context) => {
       const page = await context.newPage(
         request.params.background,
@@ -251,6 +255,7 @@ export const navigatePage = definePageTool(args => {
         : {}),
       ...timeoutSchema,
     },
+    blockedByDialog: false,
     handler: async (request, response) => {
       const page = request.page;
       const options = {
@@ -385,6 +390,7 @@ export const resizePage = definePageTool({
     width: zod.number().describe('Page width'),
     height: zod.number().describe('Page height'),
   },
+  blockedByDialog: false,
   handler: async (request, response, _context) => {
     const page = request.page;
 
@@ -429,6 +435,7 @@ export const handleDialog = definePageTool({
       .optional()
       .describe('Optional prompt text to enter into the dialog.'),
   },
+  blockedByDialog: false,
   handler: async (request, response, _context) => {
     const page = request.page;
     const dialog = page.getDialog();
@@ -479,6 +486,7 @@ export const getTabId = definePageTool({
         `The ID of the page to get the tab ID for. Call ${listPages().name} to get available pages.`,
       ),
   },
+  blockedByDialog: false,
   handler: async (request, response, context) => {
     const page = context.getPageById(request.params.pageId);
     const tabId = (page.pptrPage as unknown as CdpPage)._tabId;

src/tools/performance.ts

@@ -48,6 +48,7 @@ export const startTrace = definePageTool({
       ),
     filePath: filePathSchema,
   },
+  blockedByDialog: true,
   handler: async (request, response, context) => {
     context.validatePath(request.params.filePath);
     if (context.isRunningPerformanceTrace()) {
@@ -126,6 +127,7 @@ export const stopTrace = definePageTool({
   schema: {
     filePath: filePathSchema,
   },
+  blockedByDialog: true,
   handler: async (request, response, context) => {
     context.validatePath(request.params.filePath);
     if (!context.isRunningPerformanceTrace()) {
@@ -161,6 +163,7 @@ export const analyzeInsight = definePageTool({
         'The name of the Insight you want more information on. For example: "DocumentLatency" or "LCPBreakdown"',
       ),
   },
+  blockedByDialog: false,
   handler: async (request, response, context) => {
     const lastRecording = context.recordedTraces().at(-1);
     if (!lastRecording) {

src/tools/screencast.ts

@@ -28,7 +28,6 @@ export const startScreencast = definePageTool(args => ({
   annotations: {
     category: ToolCategory.DEBUGGING,
     readOnlyHint: false,
-
     conditions: ['screencast'],
   },
   schema: {
@@ -39,6 +38,7 @@ export const startScreencast = definePageTool(args => ({
         `Output file path (${supportedExtensions.join(',')} are supported). Uses mkdtemp to generate a unique path if not provided.`,
       ),
   },
+  blockedByDialog: false,
   handler: async (request, response, context) => {
     context.validatePath(request.params.filePath);
     if (context.getScreenRecorder() !== null) {
@@ -102,6 +102,7 @@ export const stopScreencast = definePageTool({
     conditions: ['screencast'],
   },
   schema: {},
+  blockedByDialog: false,
   handler: async (_request, response, context) => {
     const data = context.getScreenRecorder();
     if (!data) {

src/tools/screenshot.ts

@@ -50,6 +50,7 @@ export const screenshot = definePageTool({
         'The absolute path, or a path relative to the current working directory, to save the screenshot to instead of attaching it to the response.',
       ),
   },
+  blockedByDialog: true,
   handler: async (request, response, context) => {
     context.validatePath(request.params.filePath);
     if (request.params.uid && request.params.fullPage) {

src/tools/script.ts

@@ -64,6 +64,7 @@ Example with arguments: \`(el) => {
           }
         : {}),
     },
+    blockedByDialog: true,
     handler: async (request, response, context) => {
       const {
         serviceWorkerId,

src/tools/slim/tools.ts

@@ -18,6 +18,7 @@ export const screenshot = definePageTool({
     readOnlyHint: false,
   },
   schema: {},
+  blockedByDialog: true,
   handler: async (request, response, context) => {
     const page = request.page;
     const screenshot = await page.pptrPage.screenshot({
@@ -42,6 +43,7 @@ export const navigate = definePageTool({
   schema: {
     url: zod.string().describe('URL to navigate to'),
   },
+  blockedByDialog: false,
   handler: async (request, response) => {
     const page = request.page;
 
@@ -79,6 +81,7 @@ export const evaluate = definePageTool({
   schema: {
     script: zod.string().describe(`JS script to run on the page`),
   },
+  blockedByDialog: true,
   handler: async (request, response) => {
     const page = request.page;
     try {

src/tools/snapshot.ts

@@ -33,6 +33,7 @@ in the DevTools Elements panel (if any).`,
         'The absolute path, or a path relative to the current working directory, to save the snapshot to instead of attaching it to the response.',
       ),
   },
+  blockedByDialog: true,
   handler: async (request, response, context) => {
     context.validatePath(request.params.filePath);
     response.includeSnapshot({
@@ -58,6 +59,7 @@ export const waitFor = definePageTool({
       ),
     ...timeoutSchema,
   },
+  blockedByDialog: true,
   handler: async (request, response, context) => {
     const page = request.page;
     await context.waitForTextOnPage(

src/tools/webmcp.ts

@@ -18,6 +18,7 @@ export const listWebMcpTools = definePageTool({
     conditions: ['experimentalWebmcp'],
   },
   schema: {},
+  blockedByDialog: false,
   handler: async (_request, response, _context) => {
     response.setListWebMcpTools();
   },
@@ -38,6 +39,7 @@ export const executeWebMcpTool = definePageTool({
       .optional()
       .describe('The JSON-stringified parameters to pass to the WebMCP tool'),
   },
+  blockedByDialog: false,
   handler: async (request, response) => {
     const toolName = request.params.toolName;
 

tests/index.test.js.snapshot

@@ -1,3 +1,15 @@
+exports[`e2e > Dialogs > returns blocked message when dialog is opened during tool execution 1`] = `
+{"content":[{"type":"text","text":"# Open dialog\\nalert: test dialog.\\nCall handle_dialog to handle it before continuing.\\nError: Failed to interact with the element with uid 1_1. The element did not become interactive within the configured timeout."}],"isError":true}
+`;
+
+exports[`e2e > Dialogs > when dialog is open and tool is blocked, returns an error 1`] = `
+{"content":[{"type":"text","text":"# Open dialog\\nalert: test dialog.\\nCall handle_dialog to handle it before continuing.\\nError: A dialog is open (alert: test dialog)."}],"isError":true}
+`;
+
+exports[`e2e > Dialogs > when dialog is open and tool is not blocked, executes tool 1`] = `
+{"content":[{"type":"text","text":"# Open dialog\\nalert: test dialog.\\nCall handle_dialog to handle it before continuing.\\n## Pages\\n1: about:blank\\n2: data:text/html,<button id=\\"test\\" onclick=\\"alert('test dialog')\\">Click me</button>\\n3: data:text/html,<h1>New</h1> [selected]"}]}
+`;
+
 exports[`e2e > calls a tool 1`] = `
 [{"type":"text","text":"## Pages\\n1: about:blank [selected]"}]
 `;
@@ -5,7 +17,3 @@ exports[`e2e > calls a tool 1`] = `
 exports[`e2e > calls a tool multiple times 1`] = `
 [{"type":"text","text":"## Pages\\n1: about:blank [selected]"}]
 `;
-
-exports[`e2e > returns blocked message when dialog is opened during tool execution 1`] = `
-{"content":[{"type":"text","text":"# Open dialog\\nalert: test dialog.\\nCall handle_dialog to handle it before continuing.\\nError: Failed to interact with the element with uid 1_1. The element did not become interactive within the configured timeout."}],"isError":true}
-`;

tests/index.test.ts

@@ -246,8 +246,8 @@ describe('e2e', () => {
     );
   });
 
-  it('returns blocked message when dialog is opened during tool execution', async t => {
-    await withClient(async client => {
+  describe('Dialogs', () => {
+    async function createNewPageAndTriggerDialog(client: Client) {
       // Navigate to a page with a button that triggers a dialog on click
       await client.callTool({
         name: 'new_page',
@@ -273,7 +273,42 @@ describe('e2e', () => {
         },
       });
 
-      t.assert.snapshot?.(JSON.stringify(result));
+      return result;
+    }
+
+    it('returns blocked message when dialog is opened during tool execution', async t => {
+      await withClient(async client => {
+        const result = await createNewPageAndTriggerDialog(client);
+        t.assert.snapshot?.(JSON.stringify(result));
+      });
+    });
+
+    it('when dialog is open and tool is blocked, returns an error', async t => {
+      await withClient(async client => {
+        await createNewPageAndTriggerDialog(client);
+        const result = await client.callTool({
+          name: 'take_screenshot',
+          arguments: {
+            filePath: '/tmp/test.png',
+          },
+        });
+
+        t.assert.snapshot?.(JSON.stringify(result));
+      });
+    });
+
+    it('when dialog is open and tool is not blocked, executes tool', async t => {
+      await withClient(async client => {
+        await createNewPageAndTriggerDialog(client);
+        const result = await client.callTool({
+          name: 'new_page',
+          arguments: {
+            url: `data:text/html,<h1>New</h1>`,
+          },
+        });
+
+        t.assert.snapshot?.(JSON.stringify(result));
+      });
     });
   });
 });

tests/telemetry/toolMetricsUtils.test.ts

@@ -46,6 +46,7 @@ describe('toolMetricsUtils', () => {
           argStr: zod.string(),
           uid: zod.string(), // Should be blocked
         },
+        blockedByDialog: false,
         handler: async () => {
           // no-op
         },
@@ -70,6 +71,7 @@ describe('toolMetricsUtils', () => {
         schema: {
           argEnum: zod.enum(['foo', 'bar']),
         },
+        blockedByDialog: false,
         handler: async () => {
           // no-op
         },