diff --git a/packages/forms/signals/src/webmcp/registration.ts b/packages/forms/signals/src/webmcp/registration.ts
index 5653d3c814f..bc38529a879 100644
--- a/packages/forms/signals/src/webmcp/registration.ts
+++ b/packages/forms/signals/src/webmcp/registration.ts
@@ -55,6 +55,15 @@ async function initWebMcpForm(
       name: options.name,
       description: options.description,
       inputSchema,
+      annotations: {
+        // Forms are assumed to implicitly mutate the DOM (otherwise how would a user interact with them?)
+        // and therefore are _never_ read-only.
+        readOnlyHint: false,
+
+        // Response text is currently hard-coded by the framework and trusted or derived from application
+        // errors which are considered trusted.
+        untrustedContentHint: false,
+      },
       execute: async (args: Record<string, unknown>) => {
         // Populate the form with changes from the agent.
         node.value.set(args);
diff --git a/packages/forms/signals/test/web/webmcp.spec.ts b/packages/forms/signals/test/web/webmcp.spec.ts
index b92d763d785..6e6ba789183 100644
--- a/packages/forms/signals/test/web/webmcp.spec.ts
+++ b/packages/forms/signals/test/web/webmcp.spec.ts
@@ -40,6 +40,9 @@ describe('Signal Forms WebMCP Integration', () => {
         },
       });
 
+      const modelContext = (globalThis.document as any).modelContext;
+      const registerSpy = spyOn(modelContext, 'registerTool').and.callThrough();
+
       TestBed.runInInjectionContext(() => {
         form(model, {
           experimentalWebMcpTool: {
@@ -50,6 +53,16 @@ describe('Signal Forms WebMCP Integration', () => {
       });
       await TestBed.inject(ApplicationRef).whenStable();
 
+      expect(registerSpy).toHaveBeenCalledWith(
+        jasmine.objectContaining({
+          annotations: {
+            readOnlyHint: false,
+            untrustedContentHint: false,
+          },
+        }),
+        jasmine.anything(),
+      );
+
       const registeredTools = globalThis.navigator.modelContextTesting!.listTools();
       expect(registeredTools[0].name).toBe('testFormTool');
       expect(registeredTools[0].description).toBe('A test form tool');