diff --git a/packages/core/src/debug/ai/signal_graph.ts b/packages/core/src/debug/ai/signal_graph.ts
index a033549c3289..0c2ea82c9f61 100644
--- a/packages/core/src/debug/ai/signal_graph.ts
+++ b/packages/core/src/debug/ai/signal_graph.ts
@@ -6,8 +6,8 @@
  * found in the LICENSE file at https://angular.dev/license
  */
 
+import {Injector} from '../../di/injector';
 import {NullInjector} from '../../di/null_injector';
-import {getInjector} from '../../render3/util/discovery_utils';
 import {DebugSignalGraph, getSignalGraph} from '../../render3/util/signal_debug';
 import {ToolDefinition} from './tool_definitions';
 
@@ -19,20 +19,19 @@ type AiSignalGraph = Omit<DebugSignalGraph, 'nodes'> & {
 /**
  * Tool that exposes Angular's signal dependency graph to AI agents.
  */
-export const signalGraphTool: ToolDefinition<{target: HTMLElement}, AiSignalGraph> = {
+export const signalGraphTool: ToolDefinition<{injector: Injector}, AiSignalGraph> = {
   name: 'angular:signal_graph',
   // tslint:disable-next-line:no-toplevel-property-access
   description: `
-Exposes the Angular signal dependency graph for a given DOM element.
+Exposes the Angular signal dependency graph for a given Injector.
 
 This tool extracts the reactive dependency graph (signals, computeds, and effects) that
-are transitive dependencies of the effects of that element. It will include signals
+are transitive dependencies of the effects of that injector. It will include signals
 authored in other components/services and depended upon by the target component, but
 will *not* include signals only used in descendant components effects.
 
 Params:
-- \`target\`: The element to get the signal graph for. Must be the host element of an
-  Angular component.
+- \`injector\`: The Injector to get the signal graph for.
 
 Returns:
 - \`nodes\`: An array of reactive nodes discovered in the context. Each node contains:
@@ -53,22 +52,19 @@ Example: An edge with \`{consumer: 2, producer: 0}\` means that \`nodes[2]\` (e.
   inputSchema: {
     type: 'object',
     properties: {
-      target: {
+      injector: {
         type: 'object',
-        description: 'The element to get the signal graph for.',
-        'x-mcp-type': 'HTMLElement',
+        description: 'The Injector to get the signal graph for.',
+        'x-mcp-type': 'Injector',
       },
     },
-    required: ['target'],
+    required: ['injector'],
   },
-  execute: async ({target}: {target: HTMLElement}) => {
-    if (!(target instanceof HTMLElement)) {
-      throw new Error('Invalid input: "target" must be an HTMLElement.');
-    }
-
-    const injector = getInjector(target);
-    if (injector instanceof NullInjector) {
-      throw new Error('Invalid input: "target" is not the host element of an Angular component.');
+  execute: async ({injector}: {injector: Injector}) => {
+    if (!injector || injector instanceof NullInjector) {
+      throw new Error(
+        'Invalid input: "injector" is undefined, null, or an instance of NullInjector',
+      );
     }
 
     const graph = getSignalGraph(injector);
diff --git a/packages/core/test/debug/ai/signal_graph_spec.ts b/packages/core/test/debug/ai/signal_graph_spec.ts
index 4b01de3017a2..b36761d8e3e3 100644
--- a/packages/core/test/debug/ai/signal_graph_spec.ts
+++ b/packages/core/test/debug/ai/signal_graph_spec.ts
@@ -10,13 +10,15 @@ import {Component, computed, effect, signal} from '@angular/core';
 import {TestBed} from '@angular/core/testing';
 import {signalGraphTool} from '../../../src/debug/ai/signal_graph';
 import {setupFrameworkInjectorProfiler} from '../../../src/render3/debug/framework_injector_profiler';
+import {getInjector} from '../../../src/render3/util/discovery_utils';
+import {Injector} from '../../../src/di/injector';
 
 describe('signalGraphTool', () => {
   beforeEach(() => {
     setupFrameworkInjectorProfiler();
   });
 
-  it('should discover signal graph from targeted element', async () => {
+  it('should discover signal graph from targeted injector', async () => {
     @Component({
       selector: 'signal-graph-test-root',
       template: '<div>Signals test: {{ double() }}</div>',
@@ -40,8 +42,9 @@ describe('signalGraphTool', () => {
     await fixture.whenStable();
 
     const rootElement = fixture.nativeElement;
+    const injector = getInjector(rootElement);
 
-    const result = await signalGraphTool.execute({target: rootElement});
+    const result = await signalGraphTool.execute({injector});
 
     expect(result.nodes).toEqual(
       jasmine.arrayWithExactContents([
@@ -66,15 +69,21 @@ describe('signalGraphTool', () => {
     );
   });
 
-  it('should throw an error if target is not an HTMLElement', async () => {
-    await expectAsync(
-      signalGraphTool.execute({target: {} as unknown as HTMLElement}),
-    ).toBeRejectedWithError(/must be an HTMLElement/);
+  it('should throw an error if injector is null', async () => {
+    await expectAsync(signalGraphTool.execute({injector: null!})).toBeRejectedWithError(
+      /undefined, null, or an instance of NullInjector/,
+    );
+  });
+
+  it('should throw an error if injector is undefined', async () => {
+    await expectAsync(signalGraphTool.execute({injector: undefined!})).toBeRejectedWithError(
+      /undefined, null, or an instance of NullInjector/,
+    );
   });
 
-  it('should throw an error if target is not an Angular component', async () => {
+  it('should throw an error if injector is a NullInjector', async () => {
     await expectAsync(
-      signalGraphTool.execute({target: document.createElement('div')}),
-    ).toBeRejectedWithError(/not the host element of an Angular component/);
+      signalGraphTool.execute({injector: getInjector(document.createElement('div'))}),
+    ).toBeRejectedWithError(/undefined, null, or an instance of NullInjector/);
   });
 });