feat(webmcp): Add support for untrustedContent WebMCPAnnotation (#14901)

docs/api/puppeteer.webmcpannotation.md

@@ -72,5 +72,24 @@ A hint indicating that the tool does not modify any state.
 
 </td><td>
 
+</td></tr>
+<tr><td>
+
+<span id="untrustedcontent">untrustedContent</span>
+
+</td><td>
+
+`optional`
+
+</td><td>
+
+boolean
+
+</td><td>
+
+A hint indicating that the tool output may contain untrusted content, ex: UGC, 3rd party data.
+
+</td><td>
+
 </td></tr>
 </tbody></table>

packages/puppeteer-core/src/cdp/WebMCP.ts

@@ -28,6 +28,11 @@ export interface WebMCPAnnotation {
    * A hint indicating that the tool does not modify any state.
    */
   readOnly?: boolean;
+  /**
+   * A hint indicating that the tool output may contain untrusted content, ex: UGC, 3rd
+   * party data.
+   */
+  untrustedContent?: boolean;
   /**
    * If the declarative tool was declared with the autosubmit attribute.
    */

test/src/cdp/webmcp.spec.ts

@@ -47,8 +47,10 @@ describe('Page.webmcp', function () {
           },
           required: ['text'],
         },
-        execute: () => {},
-        annotations: {readOnlyHint: true},
+        execute: (params: {text: string}) => {
+          return params.text;
+        },
+        annotations: {readOnlyHint: true, untrustedContentHint: true},
       });
     });
     // Register a declarative WebMCP tool.
@@ -75,6 +77,7 @@ describe('Page.webmcp', function () {
     });
     expect(tools[0]!.annotations).toBeDefined();
     expect(tools[0]!.annotations!.readOnly).toBe(true);
+    expect(tools[0]!.annotations!.untrustedContent).toBe(true);
     expect(tools[0]!.frame).toBe(page.mainFrame());
     expect(await tools[0]!.formElement).toBeUndefined();
     expect(tools[0]!.location).toBeDefined();