Add initial MCP version with SDK imports

config/gni/devtools_grd_files.gni

@@ -638,6 +638,8 @@ grd_files_bundled_sources = [
   "front_end/panels/ai_chat/core/PageInfoManager.js",
   "front_end/panels/ai_chat/core/AgentNodes.js",
   "front_end/panels/ai_chat/core/GraphHelpers.js",
+  "front_end/panels/ai_chat/core/ToolSurfaceProvider.js",
+  "front_end/panels/ai_chat/core/ToolNameMap.js",
   "front_end/panels/ai_chat/core/StateGraph.js",
   "front_end/panels/ai_chat/core/Logger.js",
   "front_end/panels/ai_chat/core/AgentErrorHandler.js",
@@ -723,6 +725,11 @@ grd_files_bundled_sources = [
   "front_end/panels/ai_chat/evaluation/utils/PromptTemplates.js",
   "front_end/panels/ai_chat/evaluation/utils/ResponseParsingUtils.js",
   "front_end/panels/ai_chat/evaluation/utils/SanitizationUtils.js",
+  "front_end/panels/ai_chat/mcp/MCPConfig.js",
+  "front_end/panels/ai_chat/mcp/MCPRegistry.js",
+  "front_end/panels/ai_chat/mcp/MCPToolAdapter.js",
+  "front_end/panels/ai_chat/mcp/MCPMetaTools.js",
+  "front_end/panels/ai_chat/tools/LLMTracingWrapper.js",
   "front_end/panels/animation/animation-meta.js",
   "front_end/panels/animation/animation.js",
   "front_end/panels/application/application-meta.js",
@@ -860,6 +867,7 @@ grd_files_bundled_sources = [
   "front_end/third_party/lighthouse/lighthouse-dt-bundle.js",
   "front_end/third_party/lighthouse/report/report.js",
   "front_end/third_party/lit/lit.js",
+  "front_end/third_party/mcp-sdk/mcp-sdk.js",
   "front_end/third_party/marked/marked.js",
   "front_end/third_party/puppeteer-replay/puppeteer-replay.js",
   "front_end/third_party/puppeteer/puppeteer.js",
@@ -1372,6 +1380,7 @@ grd_files_unbundled_sources = [
   "front_end/panels/ai_assistance/components/ChatView.js",
   "front_end/panels/ai_assistance/components/ExploreWidget.js",
   "front_end/panels/ai_assistance/components/MarkdownRendererWithCodeBlock.js",
+  "front_end/panels/ai_assistance/components/ScrollPinHelper.js",
   "front_end/panels/ai_assistance/components/UserActionRow.js",
   "front_end/panels/ai_assistance/components/chatView.css.js",
   "front_end/panels/ai_assistance/components/exploreWidget.css.js",
@@ -2201,6 +2210,16 @@ grd_files_unbundled_sources = [
   "front_end/third_party/lit/lib/lit.js",
   "front_end/third_party/lit/lib/static-html.js",
   "front_end/third_party/marked/package/lib/marked.esm.js",
+  "front_end/third_party/mcp-sdk/ajv/dist/ajv.js",
+  "front_end/third_party/mcp-sdk/eventsource-parser/package/dist/index.js",
+  "front_end/third_party/mcp-sdk/eventsource-parser/package/dist/stream.js",
+  "front_end/third_party/mcp-sdk/package/dist/client/index.js",
+  "front_end/third_party/mcp-sdk/package/dist/client/sse.js",
+  "front_end/third_party/mcp-sdk/package/dist/shared/protocol.js",
+  "front_end/third_party/mcp-sdk/package/dist/shared/transport.js",
+  "front_end/third_party/mcp-sdk/package/dist/types.js",
+  "front_end/third_party/mcp-sdk/zod/lib/index.js",
+  "front_end/third_party/mcp-sdk/zod/lib/index.mjs",
   "front_end/third_party/puppeteer-replay/package/lib/main.js",
   "front_end/third_party/puppeteer/package/lib/esm/puppeteer/api/Browser.js",
   "front_end/third_party/puppeteer/package/lib/esm/puppeteer/api/BrowserContext.js",

front_end/panels/ai_chat/BUILD.gn

@@ -55,6 +55,8 @@ devtools_module("ai_chat") {
     "core/PageInfoManager.ts",
     "core/AgentNodes.ts",
     "core/GraphHelpers.ts",
+    "core/ToolNameMap.ts",
+    "core/ToolSurfaceProvider.ts",
     "core/StateGraph.ts",
     "core/Logger.ts",
     "core/AgentErrorHandler.ts",
@@ -122,6 +124,10 @@ devtools_module("ai_chat") {
     "tracing/TracingConfig.ts",
     "auth/PKCEUtils.ts",
     "auth/OpenRouterOAuth.ts",
+    "mcp/MCPConfig.ts",
+    "mcp/MCPToolAdapter.ts",
+    "mcp/MCPRegistry.ts",
+    "mcp/MCPMetaTools.ts",
   ]
 
   deps = [
@@ -131,6 +137,7 @@ devtools_module("ai_chat") {
     "../../core/sdk:bundle",
     "../../generated:protocol",
     "../../models/logs:bundle",
+    "../../third_party/mcp-sdk:bundle",
     "../../ui/components/helpers:bundle",
     "../../ui/components/markdown_view:bundle",
     "../../ui/components/snackbars:bundle",
@@ -183,6 +190,8 @@ _ai_chat_sources = [
     "core/PageInfoManager.ts",
     "core/AgentNodes.ts",
     "core/GraphHelpers.ts",
+    "core/ToolNameMap.ts",
+    "core/ToolSurfaceProvider.ts",
     "core/StateGraph.ts",
     "core/Logger.ts",
     "core/AgentErrorHandler.ts",
@@ -200,6 +209,7 @@ _ai_chat_sources = [
     "LLM/MessageSanitizer.ts",
     "LLM/LLMClient.ts",
     "tools/Tools.ts",
+    "tools/LLMTracingWrapper.ts",
     "tools/CritiqueTool.ts",
     "tools/FetcherTool.ts",
     "tools/FinalizeWithCritiqueTool.ts",
@@ -249,6 +259,10 @@ _ai_chat_sources = [
     "tracing/TracingConfig.ts",
     "auth/PKCEUtils.ts",
     "auth/OpenRouterOAuth.ts",
+    "mcp/MCPConfig.ts",
+    "mcp/MCPToolAdapter.ts",
+    "mcp/MCPRegistry.ts",
+    "mcp/MCPMetaTools.ts",
 ]
 
 # Construct the expected JS output paths for the metadata
@@ -345,6 +359,8 @@ ts_library("unittests") {
     "agent_framework/__tests__/AgentRunner.sanitizeToolResult.test.ts",
     "agent_framework/__tests__/AgentRunner.computeToolResultText.test.ts",
     "agent_framework/__tests__/AgentRunner.run.flows.test.ts",
+    "mcp/MCPClientSDK.test.ts",
+    "core/ToolSurfaceProvider.test.ts",
   ]
 
   deps = [

front_end/panels/ai_chat/agent_framework/AgentRunner.ts

@@ -977,6 +977,7 @@ export class AgentRunner {
               logger.info(`${agentName} Executing tool: ${toolToExecute.name}`);
               const execTracingContext = getCurrentTracingContext();
               toolResultData = await toolToExecute.execute(toolArgs as any, ({
+                apiKey: config.apiKey,
                 provider: config.provider,
                 model: modelName,
                 miniModel: config.miniModel,

front_end/panels/ai_chat/agent_framework/ConfigurableAgentTool.ts

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import { AgentService } from '../core/AgentService.js';
 import type { Tool } from '../tools/Tools.js';
 import { ChatMessageEntity, type ChatMessage } from '../models/ChatTypes.js';
 import { createLogger } from '../core/Logger.js';
@@ -17,6 +16,7 @@ import { AgentRunner, type AgentRunnerConfig, type AgentRunnerHooks } from './Ag
 
 // Context passed along with agent/tool calls
 export interface CallCtx {
+  apiKey?: string,
   provider?: LLMProvider,
   model?: string,
   miniModel?: string,
@@ -196,7 +196,7 @@ export class ToolRegistry {
     try {
         const instance = factory();
         this.registeredTools.set(name, instance);
-        logger.info('Registered and instantiated tool: ${name}');
+        logger.info(`Registered and instantiated tool: ${name}`);
     } catch (error) {
         logger.error(`Failed to instantiate tool '${name}' during registration:`, error);
         // Remove the factory entry if instantiation fails
@@ -402,8 +402,8 @@ export class ConfigurableAgentTool implements Tool<ConfigurableAgentArgs, Config
 
     // Get current tracing context for debugging
     const tracingContext = getCurrentTracingContext();
-    const agentService = AgentService.getInstance();
-    const apiKey = agentService.getApiKey();
+    const callCtx = (_ctx || {}) as CallCtx;
+    const apiKey = callCtx.apiKey;
 
     if (!apiKey) {
       const errorResult = this.createErrorResult(`API key not configured for ${this.name}`, [], 'error');
@@ -427,9 +427,6 @@ export class ConfigurableAgentTool implements Tool<ConfigurableAgentArgs, Config
     // Initialize
     const maxIterations = this.config.maxIterations || 10;
 
-    // Parse execution context first
-    const callCtx = (_ctx || {}) as CallCtx;
-
     // Resolve model name from context or configuration
     let modelName: string;
     if (this.config.modelName === MODEL_SENTINELS.USE_MINI) {

front_end/panels/ai_chat/agent_framework/implementation/ConfiguredAgents.ts

@@ -19,6 +19,7 @@ import { WaitTool } from '../../tools/Tools.js';
 import { MODEL_SENTINELS } from '../../core/Constants.js';
 import { ThinkingTool } from '../../tools/ThinkingTool.js';
 import type { Tool } from '../../tools/Tools.js';
+import { registerMCPMetaTools } from '../../mcp/MCPMetaTools.js';
 
 /**
  * Configuration for the Direct URL Navigator Agent
@@ -93,6 +94,8 @@ Remember: Always use navigate_url to actually go to the constructed URLs. Return
  * Initialize all configured agents
  */
 export function initializeConfiguredAgents(): void {
+  // Ensure MCP meta-tools are available regardless of mode; selection logic decides if they are surfaced
+  registerMCPMetaTools();
   // Register core tools
   ToolRegistry.registerToolFactory('navigate_url', () => new NavigateURLTool());
   ToolRegistry.registerToolFactory('navigate_back', () => new NavigateBackTool());

front_end/panels/ai_chat/core/AgentNodes.test.ts

@@ -0,0 +1,204 @@
+// Copyright 2025 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import { createToolExecutorNode } from './AgentNodes.js';
+import { ConfigurableAgentTool } from '../agent_framework/ConfigurableAgentTool.js';
+import { ChatMessageEntity } from '../ui/ChatView.js';
+import type { AgentState } from './State.js';
+import type { ConfigurableAgentResult } from '../agent_framework/ConfigurableAgentTool.js';
+
+declare global {
+  function describe(name: string, fn: () => void): void;
+  function it(name: string, fn: () => void): void;
+  function beforeEach(fn: () => void): void;
+  function afterEach(fn: () => void): void;
+  namespace assert {
+    function strictEqual(actual: unknown, expected: unknown): void;
+    function deepEqual(actual: unknown, expected: unknown): void;
+    function isTrue(value: unknown): void;
+    function isFalse(value: unknown): void;
+    function doesNotMatch(actual: string, regexp: RegExp): void;
+  }
+}
+
+describe('AgentNodes ToolExecutorNode', () => {
+  describe('ConfigurableAgentTool result filtering', () => {
+    it('should filter out agentSession data from error results', async () => {
+      // Create a mock ConfigurableAgentTool that returns error with intermediateSteps
+      const mockAgentSession = {
+        sessionId: 'test-session-123',
+        agentName: 'test-agent',
+        status: 'error',
+        messages: [
+          { id: '1', type: 'tool_call', content: { toolName: 'test_tool' } },
+          { id: '2', type: 'tool_result', content: { result: 'test result' } }
+        ],
+        // This contains sensitive data that should not leak to LLM
+        nestedSessions: [],
+        tools: [],
+        startTime: new Date(),
+        endTime: new Date(),
+        terminationReason: 'max_iterations'
+      };
+
+      const errorResultWithSession: ConfigurableAgentResult & { agentSession: any } = {
+        success: false,
+        error: 'Agent reached maximum iterations',
+        terminationReason: 'max_iterations',
+        // This is the problematic field that contains session data
+        intermediateSteps: [
+          { entity: ChatMessageEntity.USER, text: 'test query' },
+          { entity: ChatMessageEntity.AGENT_SESSION, agentSession: mockAgentSession, summary: 'test' }
+        ],
+        agentSession: mockAgentSession
+      };
+
+      // Create mock ConfigurableAgentTool
+      class MockConfigurableAgentTool extends ConfigurableAgentTool {
+        constructor() {
+          super({
+            name: 'mock_agent',
+            description: 'Mock agent for testing',
+            systemPrompt: 'Test prompt',
+            tools: [],
+            schema: { type: 'object', properties: {}, required: [] }
+          });
+        }
+
+        async execute(): Promise<ConfigurableAgentResult & { agentSession: any }> {
+          return errorResultWithSession;
+        }
+      }
+
+      const mockTool = new MockConfigurableAgentTool();
+
+      // Create initial state with a tool call message
+      const initialState: AgentState = {
+        messages: [
+          {
+            entity: ChatMessageEntity.MODEL,
+            action: 'tool',
+            toolName: 'mock_agent',
+            toolArgs: { query: 'test' },
+            toolCallId: 'test-call-id',
+            isFinalAnswer: false
+          }
+        ],
+        agentType: 'web_task',
+        context: {}
+      };
+
+      // Create modified state with mock tool in registry
+      const stateWithMockTool = {
+        ...initialState,
+        // We need to mock the tool registry or provide tools directly
+        tools: [mockTool]
+      };
+
+      // Create ToolExecutorNode
+      const toolExecutorNode = createToolExecutorNode(stateWithMockTool);
+
+      // Execute the node
+      const result = await toolExecutorNode.invoke(stateWithMockTool);
+
+      // Verify the result
+      assert.isTrue(result.messages.length > initialState.messages.length, 'Should add tool result message');
+
+      const toolResultMessage = result.messages[result.messages.length - 1];
+      assert.strictEqual(toolResultMessage.entity, ChatMessageEntity.TOOL_RESULT);
+
+      // The critical test: resultText should NOT contain agentSession data
+      const resultText = (toolResultMessage as any).resultText;
+      assert.strictEqual(resultText, 'Error: Agent reached maximum iterations');
+
+      // Verify that the resultText does not contain session data
+      assert.doesNotMatch(resultText, /sessionId/);
+      assert.doesNotMatch(resultText, /test-session-123/);
+      assert.doesNotMatch(resultText, /intermediateSteps/);
+      assert.doesNotMatch(resultText, /agentSession/);
+      assert.doesNotMatch(resultText, /nestedSessions/);
+
+      // The resultText should be clean and only contain the error message
+      assert.strictEqual(resultText.includes('test-session-123'), false);
+    });
+
+    it('should filter out agentSession data from success results', async () => {
+      // Create a success result with intermediateSteps containing session data
+      const mockAgentSession = {
+        sessionId: 'success-session-456',
+        agentName: 'success-agent',
+        status: 'completed',
+        messages: [],
+        nestedSessions: [],
+        tools: [],
+        startTime: new Date(),
+        endTime: new Date(),
+        terminationReason: 'final_answer'
+      };
+
+      const successResultWithSession: ConfigurableAgentResult & { agentSession: any } = {
+        success: true,
+        output: 'Task completed successfully',
+        terminationReason: 'final_answer',
+        // This should not leak to LLM
+        intermediateSteps: [
+          { entity: ChatMessageEntity.AGENT_SESSION, agentSession: mockAgentSession, summary: 'test' }
+        ],
+        agentSession: mockAgentSession
+      };
+
+      class MockSuccessAgentTool extends ConfigurableAgentTool {
+        constructor() {
+          super({
+            name: 'mock_success_agent',
+            description: 'Mock success agent for testing',
+            systemPrompt: 'Test prompt',
+            tools: [],
+            schema: { type: 'object', properties: {}, required: [] }
+          });
+        }
+
+        async execute(): Promise<ConfigurableAgentResult & { agentSession: any }> {
+          return successResultWithSession;
+        }
+      }
+
+      const mockTool = new MockSuccessAgentTool();
+
+      const initialState: AgentState = {
+        messages: [
+          {
+            entity: ChatMessageEntity.MODEL,
+            action: 'tool',
+            toolName: 'mock_success_agent',
+            toolArgs: { query: 'test' },
+            toolCallId: 'test-call-id-2',
+            isFinalAnswer: false
+          }
+        ],
+        agentType: 'web_task',
+        context: {}
+      };
+
+      const stateWithMockTool = {
+        ...initialState,
+        tools: [mockTool]
+      };
+
+      const toolExecutorNode = createToolExecutorNode(stateWithMockTool);
+      const result = await toolExecutorNode.invoke(stateWithMockTool);
+
+      const toolResultMessage = result.messages[result.messages.length - 1];
+      const resultText = (toolResultMessage as any).resultText;
+
+      // Should contain only the clean output
+      assert.strictEqual(resultText, 'Task completed successfully');
+
+      // Should NOT contain session data
+      assert.doesNotMatch(resultText, /success-session-456/);
+      assert.doesNotMatch(resultText, /intermediateSteps/);
+      assert.doesNotMatch(resultText, /agentSession/);
+    });
+  });
+});