chore: Add execute_in_page_tool tool (#1766)

This allows the MCP server to call the in-page tools provided by the
inspected page.

Handling of (non-serializable) DOM elements as tool parameters or tool
output will be added in follow-ups.

Author: wolfib

src/McpContext.ts

@@ -31,6 +31,7 @@ import type {
 } from './third_party/index.js';
 import {Locator} from './third_party/index.js';
 import {PredefinedNetworkConditions} from './third_party/index.js';
+import type {ToolGroup, ToolDefinition} from './tools/inPage.js';
 import {listPages} from './tools/pages.js';
 import {CLOSE_PAGE_ERROR} from './tools/ToolDefinition.js';
 import type {Context, DevToolsData} from './tools/ToolDefinition.js';
@@ -101,6 +102,7 @@ export class McpContext implements Context {
   #screenRecorderData: {recorder: ScreenRecorder; filePath: string} | null =
     null;
 
+  #inPageTools?: ToolGroup<ToolDefinition>;
   #nextPageId = 1;
   #extensionPages = new WeakMap<Target, Page>();
 
@@ -464,6 +466,14 @@ export class McpContext implements Context {
     this.#updateSelectedPageTimeouts();
   }
 
+  setInPageTools(toolGroup?: ToolGroup<ToolDefinition>) {
+    this.#inPageTools = toolGroup;
+  }
+
+  getInPageTools(): ToolGroup<ToolDefinition> | undefined {
+    return this.#inPageTools;
+  }
+
   #updateSelectedPageTimeouts() {
     const page = this.#getSelectedMcpPage();
     // For waiters 5sec timeout should be sufficient.

src/McpResponse.ts

@@ -422,6 +422,7 @@ export class McpResponse implements Response {
     let inPageTools: ToolGroup<ToolDefinition> | undefined;
     if (this.#listInPageTools) {
       inPageTools = await getToolGroup(context.getSelectedMcpPage());
+      context.setInPageTools(inPageTools);
     }
 
     let consoleMessages: Array<ConsoleFormatter | IssueFormatter> | undefined;

src/third_party/index.ts

@@ -30,6 +30,7 @@ export {
   type TextContent,
 } from '@modelcontextprotocol/sdk/types.js';
 export {z as zod} from 'zod';
+export {default as ajv} from 'ajv';
 export {
   Locator,
   PredefinedNetworkConditions,

src/tools/ToolDefinition.ts

@@ -24,6 +24,10 @@ import type {InstalledExtension} from '../utils/ExtensionRegistry.js';
 import type {PaginationOptions} from '../utils/types.js';
 
 import type {ToolCategory} from './categories.js';
+import type {
+  ToolGroup,
+  ToolDefinition as InPageToolDefinition,
+} from './inPage.js';
 
 export interface BaseToolDefinition<
   Schema extends zod.ZodRawShape = zod.ZodRawShape,
@@ -194,6 +198,7 @@ export type Context = Readonly<{
   triggerExtensionAction(id: string): Promise<void>;
   listExtensions(): InstalledExtension[];
   getExtension(id: string): InstalledExtension | undefined;
+  getInPageTools(): ToolGroup<InPageToolDefinition> | undefined;
   getSelectedMcpPage(): McpPage;
   getExtensionServiceWorkers(): ExtensionServiceWorker[];
   getExtensionServiceWorkerId(

src/tools/inPage.ts

@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import {type JSONSchema7} from '../third_party/index.js';
+import {zod, ajv, type JSONSchema7} from '../third_party/index.js';
 
 import {ToolCategory} from './categories.js';
 import {definePageTool} from './ToolDefinition.js';
@@ -37,9 +37,13 @@ declare global {
 
 export const listInPageTools = definePageTool({
   name: 'list_in_page_tools',
-  description: `Lists all in-page-tools the page exposes for providing runtime information.
-  To call 'list_in_page_tools', call 'evaluate_script' with
-  'window.__dtmcp.executeTool("list_in_page_tools", {})'.`,
+  description: `Lists all in-page tools the page exposes for providing runtime information.
+  In-page tools can be called via the 'execute_in_page_tool()' MCP tool.
+  Alternatively, in-page tools can be executed by calling 'evaluate_script' and adding the
+  following command to the script:
+  'window.__dtmcp.executeTool(toolName, params)'
+  This might be helpful when the in-page-tools return non-serializable values or when composing
+  the in-page-tools with additional functionality.`,
   annotations: {
     category: ToolCategory.IN_PAGE,
     readOnlyHint: true,
@@ -50,3 +54,68 @@ export const listInPageTools = definePageTool({
     response.setListInPageTools();
   },
 });
+
+export const executeInPageTool = definePageTool({
+  name: 'execute_in_page_tool',
+  description: `Executes a tool exposed by the page.`,
+  annotations: {
+    category: ToolCategory.IN_PAGE,
+    readOnlyHint: false,
+    conditions: ['inPageTools'],
+  },
+  schema: {
+    toolName: zod.string().describe('The name of the tool to execute'),
+    params: zod
+      .string()
+      .optional()
+      .describe('The JSON-stringified parameters to pass to the tool'),
+  },
+  handler: async (request, response, context) => {
+    const page = context.getSelectedMcpPage();
+    const toolName = request.params.toolName;
+    let params: Record<string, unknown> = {};
+    if (request.params.params) {
+      try {
+        const parsed = JSON.parse(request.params.params);
+        if (typeof parsed === 'object' && parsed !== null) {
+          params = parsed;
+        } else {
+          throw new Error('Parsed params is not an object');
+        }
+      } catch (e) {
+        const errorMessage = e instanceof Error ? e.message : String(e);
+        throw new Error(`Failed to parse params as JSON: ${errorMessage}`);
+      }
+    }
+
+    const toolGroup = context.getInPageTools();
+    const tool = toolGroup?.tools.find(t => t.name === toolName);
+    if (!tool) {
+      throw new Error(`Tool ${toolName} not found`);
+    }
+    const ajvInstance = new ajv();
+    const validate = ajvInstance.compile(tool.inputSchema);
+    const valid = validate(params);
+    if (!valid) {
+      throw new Error(
+        `Invalid parameters for tool ${toolName}: ${ajvInstance.errorsText(validate.errors)}`,
+      );
+    }
+
+    const result = await page.pptrPage.evaluate(
+      async (name, args) => {
+        if (!window.__dtmcp?.executeTool) {
+          throw new Error('No tools found on the page');
+        }
+        const toolResult = await window.__dtmcp.executeTool(name, args);
+
+        return {
+          result: toolResult,
+        };
+      },
+      toolName,
+      params,
+    );
+    response.appendResponseLine(JSON.stringify(result, null, 2));
+  },
+});

src/tools/input.ts

@@ -217,6 +217,7 @@ async function fillFormElement(
   }
 }
 
+// here
 export const fill = definePageTool({
   name: 'fill',
   description: `Type text into a input, text area or select an option from a <select> element.`,

tests/third_party_notices.test.js.snapshot

@@ -765,6 +765,56 @@ The above copyright notice and this permission notice shall be included in all c
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 
+-------------------- DEPENDENCY DIVIDER --------------------
+
+Name: uri-js
+URL: https://github.com/garycourt/uri-js
+Version: <VERSION>
+License: BSD-2-Clause
+
+Copyright 2011 Gary Court. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
+
+1.	Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
+
+2.	Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY GARY COURT "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GARY COURT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+The views and conclusions contained in the software and documentation are those of the authors and should not be interpreted as representing official policies, either expressed or implied, of Gary Court.
+
+
+-------------------- DEPENDENCY DIVIDER --------------------
+
+Name: fast-json-stable-stringify
+URL: https://github.com/epoberezkin/fast-json-stable-stringify
+Version: <VERSION>
+License: MIT
+
+This software is released under the MIT license:
+
+Copyright (c) 2017 Evgeny Poberezkin
+Copyright (c) 2013 James Halliday
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+
 -------------------- DEPENDENCY DIVIDER --------------------
 
 Name: puppeteer-core