feat(core): add tools to list and read MCP resources (#25395)

packages/core/src/config/config.ts

@@ -30,6 +30,8 @@ import { ResourceRegistry } from '../resources/resource-registry.js';
 import { ToolRegistry } from '../tools/tool-registry.js';
 import { LSTool } from '../tools/ls.js';
 import { ReadFileTool } from '../tools/read-file.js';
+import { ReadMcpResourceTool } from '../tools/read-mcp-resource.js';
+import { ListMcpResourcesTool } from '../tools/list-mcp-resources.js';
 import { GrepTool } from '../tools/grep.js';
 import { canUseRipgrep, RipGrepTool } from '../tools/ripGrep.js';
 import { GlobTool } from '../tools/glob.js';
@@ -3579,6 +3581,12 @@ export class Config implements McpContext, AgentLoopContext {
     maybeRegister(WebFetchTool, () =>
       registry.registerTool(new WebFetchTool(this, this.messageBus)),
     );
+    maybeRegister(ReadMcpResourceTool, () =>
+      registry.registerTool(new ReadMcpResourceTool(this, this.messageBus)),
+    );
+    maybeRegister(ListMcpResourcesTool, () =>
+      registry.registerTool(new ListMcpResourcesTool(this, this.messageBus)),
+    );
     maybeRegister(ShellTool, () =>
       registry.registerTool(new ShellTool(this, this.messageBus)),
     );

packages/core/src/policy/policies/read-only.toml

@@ -47,7 +47,10 @@ toolName = [
   # Topic grouping tool is innocuous and used for UI organization.
   "update_topic",
   # Core agent lifecycle tool
-  "complete_task"
+  "complete_task",
+  # MCP resource tools
+  "read_mcp_resource",
+  "list_mcp_resources"
 ]
 decision = "allow"
 priority = 50

packages/core/src/policy/toml-loader.test.ts

@@ -1057,6 +1057,25 @@ priority = 100
           cliHelpResult.decision,
           'cli_help should be ALLOWED in Plan Mode',
         ).toBe(PolicyDecision.ALLOW);
+
+        // 7. Verify MCP resource tools are ALLOWED
+        const listMcpResult = await engine.check(
+          { name: 'list_mcp_resources' },
+          undefined,
+        );
+        expect(
+          listMcpResult.decision,
+          'list_mcp_resources should be ALLOWED in Plan Mode',
+        ).toBe(PolicyDecision.ALLOW);
+
+        const readMcpResult = await engine.check(
+          { name: 'read_mcp_resource', args: { uri: 'test://resource' } },
+          undefined,
+        );
+        expect(
+          readMcpResult.decision,
+          'read_mcp_resource should be ALLOWED in Plan Mode',
+        ).toBe(PolicyDecision.ALLOW);
       } finally {
         await fs.rm(tempPolicyDir, { recursive: true, force: true });
       }

packages/core/src/tools/definitions/base-declarations.ts

@@ -137,3 +137,7 @@ export const TOPIC_PARAM_STRATEGIC_INTENT = 'strategic_intent';
 // -- complete_task --
 export const COMPLETE_TASK_TOOL_NAME = 'complete_task';
 export const COMPLETE_TASK_DISPLAY_NAME = 'Complete Task';
+
+// -- MCP Resources --
+export const READ_MCP_RESOURCE_TOOL_NAME = 'read_mcp_resource';
+export const LIST_MCP_RESOURCES_TOOL_NAME = 'list_mcp_resources';

packages/core/src/tools/definitions/coreTools.ts

@@ -43,6 +43,8 @@ export {
   UPDATE_TOPIC_DISPLAY_NAME,
   COMPLETE_TASK_TOOL_NAME,
   COMPLETE_TASK_DISPLAY_NAME,
+  READ_MCP_RESOURCE_TOOL_NAME,
+  LIST_MCP_RESOURCES_TOOL_NAME,
   // Shared parameter names
   PARAM_FILE_PATH,
   PARAM_DIR_PATH,
@@ -280,3 +282,17 @@ export function getActivateSkillDefinition(
     overrides: (modelId) => getToolSet(modelId).activate_skill(skillNames),
   };
 }
+
+export const READ_MCP_RESOURCE_DEFINITION: ToolDefinition = {
+  get base() {
+    return DEFAULT_LEGACY_SET.read_mcp_resource;
+  },
+  overrides: (modelId) => getToolSet(modelId).read_mcp_resource,
+};
+
+export const LIST_MCP_RESOURCES_DEFINITION: ToolDefinition = {
+  get base() {
+    return DEFAULT_LEGACY_SET.list_mcp_resources;
+  },
+  overrides: (modelId) => getToolSet(modelId).list_mcp_resources,
+};

packages/core/src/tools/definitions/model-family-sets/default-legacy.ts

@@ -25,6 +25,8 @@ import {
   GET_INTERNAL_DOCS_TOOL_NAME,
   ASK_USER_TOOL_NAME,
   ENTER_PLAN_MODE_TOOL_NAME,
+  READ_MCP_RESOURCE_TOOL_NAME,
+  LIST_MCP_RESOURCES_TOOL_NAME,
   // Shared parameter names
   PARAM_FILE_PATH,
   PARAM_DIR_PATH,
@@ -756,4 +758,37 @@ The agent did not use the todo list because this task could be completed by a ti
 
   exit_plan_mode: () => getExitPlanModeDeclaration(),
   activate_skill: (skillNames) => getActivateSkillDeclaration(skillNames),
+
+  read_mcp_resource: {
+    name: READ_MCP_RESOURCE_TOOL_NAME,
+    description:
+      'Reads the content of a specified Model Context Protocol (MCP) resource.',
+    parametersJsonSchema: {
+      type: 'object',
+      properties: {
+        uri: {
+          description: 'The URI of the MCP resource to read.',
+          type: 'string',
+        },
+      },
+      required: ['uri'],
+    },
+  },
+
+  list_mcp_resources: {
+    name: LIST_MCP_RESOURCES_TOOL_NAME,
+    description:
+      'Lists all available resources exposed by connected MCP servers.',
+    parametersJsonSchema: {
+      type: 'object',
+      properties: {
+        serverName: {
+          description:
+            'Optional filter to list resources from a specific server.',
+          type: 'string',
+        },
+      },
+      required: [],
+    },
+  },
 };

packages/core/src/tools/definitions/model-family-sets/gemini-3.ts

@@ -25,6 +25,8 @@ import {
   GET_INTERNAL_DOCS_TOOL_NAME,
   ASK_USER_TOOL_NAME,
   ENTER_PLAN_MODE_TOOL_NAME,
+  READ_MCP_RESOURCE_TOOL_NAME,
+  LIST_MCP_RESOURCES_TOOL_NAME,
   // Shared parameter names
   PARAM_FILE_PATH,
   PARAM_DIR_PATH,
@@ -733,4 +735,37 @@ The agent did not use the todo list because this task could be completed by a ti
   exit_plan_mode: () => getExitPlanModeDeclaration(),
   activate_skill: (skillNames) => getActivateSkillDeclaration(skillNames),
   update_topic: getUpdateTopicDeclaration(),
+
+  read_mcp_resource: {
+    name: READ_MCP_RESOURCE_TOOL_NAME,
+    description:
+      'Reads the content of a specified Model Context Protocol (MCP) resource.',
+    parametersJsonSchema: {
+      type: 'object',
+      properties: {
+        uri: {
+          description: 'The URI of the MCP resource to read.',
+          type: 'string',
+        },
+      },
+      required: ['uri'],
+    },
+  },
+
+  list_mcp_resources: {
+    name: LIST_MCP_RESOURCES_TOOL_NAME,
+    description:
+      'Lists all available resources exposed by connected MCP servers.',
+    parametersJsonSchema: {
+      type: 'object',
+      properties: {
+        serverName: {
+          description:
+            'Optional filter to list resources from a specific server.',
+          type: 'string',
+        },
+      },
+      required: [],
+    },
+  },
 };

packages/core/src/tools/definitions/types.ts

@@ -50,5 +50,7 @@ export interface CoreToolSet {
   enter_plan_mode: FunctionDeclaration;
   exit_plan_mode: () => FunctionDeclaration;
   activate_skill: (skillNames: string[]) => FunctionDeclaration;
+  read_mcp_resource: FunctionDeclaration;
+  list_mcp_resources: FunctionDeclaration;
   update_topic?: FunctionDeclaration;
 }

packages/core/src/tools/list-mcp-resources.test.ts

@@ -0,0 +1,156 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect, beforeEach, vi, type Mock } from 'vitest';
+import { ListMcpResourcesTool } from './list-mcp-resources.js';
+import { ToolErrorType } from './tool-error.js';
+import type { AgentLoopContext } from '../config/agent-loop-context.js';
+import { createMockMessageBus } from '../test-utils/mock-message-bus.js';
+
+describe('ListMcpResourcesTool', () => {
+  let tool: ListMcpResourcesTool;
+  let mockContext: {
+    config: {
+      getMcpClientManager: Mock;
+    };
+  };
+  let mockMcpManager: {
+    getAllResources: Mock;
+  };
+  const abortSignal = new AbortController().signal;
+
+  beforeEach(() => {
+    mockMcpManager = {
+      getAllResources: vi.fn(),
+    };
+
+    mockContext = {
+      config: {
+        getMcpClientManager: vi.fn().mockReturnValue(mockMcpManager),
+      },
+    };
+
+    tool = new ListMcpResourcesTool(
+      mockContext as unknown as AgentLoopContext,
+      createMockMessageBus(),
+    );
+  });
+
+  it('should successfully list all resources', async () => {
+    const resources = [
+      {
+        uri: 'protocol://r1',
+        serverName: 'server1',
+        name: 'R1',
+        description: 'D1',
+      },
+      { uri: 'protocol://r2', serverName: 'server2', name: 'R2' },
+    ];
+    mockMcpManager.getAllResources.mockReturnValue(resources);
+
+    const invocation = (
+      tool as unknown as {
+        createInvocation: (params: Record<string, unknown>) => {
+          execute: (options: { abortSignal: AbortSignal }) => Promise<unknown>;
+        };
+      }
+    ).createInvocation({});
+    const result = (await invocation.execute({ abortSignal })) as {
+      llmContent: string;
+      returnDisplay: string;
+    };
+
+    expect(mockMcpManager.getAllResources).toHaveBeenCalled();
+    expect(result.llmContent).toContain('Available MCP Resources:');
+    expect(result.llmContent).toContain('protocol://r1');
+    expect(result.llmContent).toContain('protocol://r2');
+    expect(result.returnDisplay).toBe('Listed 2 resources.');
+  });
+
+  it('should filter by server name', async () => {
+    const resources = [
+      { uri: 'protocol://r1', serverName: 'server1', name: 'R1' },
+      { uri: 'protocol://r2', serverName: 'server2', name: 'R2' },
+    ];
+    mockMcpManager.getAllResources.mockReturnValue(resources);
+
+    const invocation = (
+      tool as unknown as {
+        createInvocation: (params: Record<string, unknown>) => {
+          execute: (options: { abortSignal: AbortSignal }) => Promise<unknown>;
+        };
+      }
+    ).createInvocation({ serverName: 'server1' });
+    const result = (await invocation.execute({ abortSignal })) as {
+      llmContent: string;
+      returnDisplay: string;
+    };
+
+    expect(result.llmContent).toContain('protocol://r1');
+    expect(result.llmContent).not.toContain('protocol://r2');
+    expect(result.returnDisplay).toBe('Listed 1 resources.');
+  });
+
+  it('should return message if no resources found', async () => {
+    mockMcpManager.getAllResources.mockReturnValue([]);
+
+    const invocation = (
+      tool as unknown as {
+        createInvocation: (params: Record<string, unknown>) => {
+          execute: (options: { abortSignal: AbortSignal }) => Promise<unknown>;
+        };
+      }
+    ).createInvocation({});
+    const result = (await invocation.execute({ abortSignal })) as {
+      llmContent: string;
+      returnDisplay: string;
+    };
+
+    expect(result.llmContent).toBe('No MCP resources found.');
+    expect(result.returnDisplay).toBe('No MCP resources found.');
+  });
+
+  it('should return message if no resources found for server', async () => {
+    mockMcpManager.getAllResources.mockReturnValue([]);
+
+    const invocation = (
+      tool as unknown as {
+        createInvocation: (params: Record<string, unknown>) => {
+          execute: (options: { abortSignal: AbortSignal }) => Promise<unknown>;
+        };
+      }
+    ).createInvocation({ serverName: 'nonexistent' });
+    const result = (await invocation.execute({ abortSignal })) as {
+      llmContent: string;
+      returnDisplay: string;
+    };
+
+    expect(result.llmContent).toBe(
+      'No resources found for server: nonexistent',
+    );
+    expect(result.returnDisplay).toBe(
+      'No resources found for server: nonexistent',
+    );
+  });
+
+  it('should return error if MCP Client Manager not available', async () => {
+    mockContext.config.getMcpClientManager.mockReturnValue(undefined);
+
+    const invocation = (
+      tool as unknown as {
+        createInvocation: (params: Record<string, unknown>) => {
+          execute: (options: { abortSignal: AbortSignal }) => Promise<unknown>;
+        };
+      }
+    ).createInvocation({});
+    const result = (await invocation.execute({ abortSignal })) as {
+      error: { type: string; message: string };
+    };
+
+    expect(result.error?.type).toBe(ToolErrorType.EXECUTION_FAILED);
+    expect(result.error?.message).toContain('MCP Client Manager not available');
+  });
+});

packages/core/src/tools/list-mcp-resources.ts

@@ -0,0 +1,123 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import {
+  BaseDeclarativeTool,
+  BaseToolInvocation,
+  Kind,
+  type ToolResult,
+  type ExecuteOptions,
+} from './tools.js';
+import type { MessageBus } from '../confirmation-bus/message-bus.js';
+import { LIST_MCP_RESOURCES_TOOL_NAME } from './tool-names.js';
+import { LIST_MCP_RESOURCES_DEFINITION } from './definitions/coreTools.js';
+import type { AgentLoopContext } from '../config/agent-loop-context.js';
+import { ToolErrorType } from './tool-error.js';
+
+export interface ListMcpResourcesParams {
+  serverName?: string;
+}
+
+export class ListMcpResourcesTool extends BaseDeclarativeTool<
+  ListMcpResourcesParams,
+  ToolResult
+> {
+  static readonly Name = LIST_MCP_RESOURCES_TOOL_NAME;
+
+  constructor(
+    private readonly context: AgentLoopContext,
+    messageBus: MessageBus,
+  ) {
+    super(
+      ListMcpResourcesTool.Name,
+      'List MCP Resources',
+      LIST_MCP_RESOURCES_DEFINITION.base.description!,
+      Kind.Search,
+      LIST_MCP_RESOURCES_DEFINITION.base.parametersJsonSchema,
+      messageBus,
+      true,
+      false,
+    );
+  }
+
+  protected createInvocation(
+    params: ListMcpResourcesParams,
+  ): ListMcpResourcesToolInvocation {
+    return new ListMcpResourcesToolInvocation(
+      this.context,
+      params,
+      this.messageBus,
+    );
+  }
+}
+
+class ListMcpResourcesToolInvocation extends BaseToolInvocation<
+  ListMcpResourcesParams,
+  ToolResult
+> {
+  constructor(
+    private readonly context: AgentLoopContext,
+    params: ListMcpResourcesParams,
+    messageBus: MessageBus,
+  ) {
+    super(params, messageBus, ListMcpResourcesTool.Name, 'List MCP Resources');
+  }
+
+  getDescription(): string {
+    return 'List MCP resources';
+  }
+
+  async execute({
+    abortSignal: _abortSignal,
+  }: ExecuteOptions): Promise<ToolResult> {
+    const mcpManager = this.context.config.getMcpClientManager();
+    if (!mcpManager) {
+      return {
+        llmContent: 'Error: MCP Client Manager not available.',
+        returnDisplay: 'Error: MCP Client Manager not available.',
+        error: {
+          message: 'MCP Client Manager not available.',
+          type: ToolErrorType.EXECUTION_FAILED,
+        },
+      };
+    }
+
+    let resources = mcpManager.getAllResources();
+
+    const serverName = this.params.serverName;
+    if (serverName) {
+      resources = resources.filter((r) => r.serverName === serverName);
+    }
+
+    if (resources.length === 0) {
+      const msg = serverName
+        ? `No resources found for server: ${serverName}`
+        : 'No MCP resources found.';
+      return {
+        llmContent: msg,
+        returnDisplay: msg,
+      };
+    }
+
+    // Format the list
+    let content = 'Available MCP Resources:\n';
+    for (const resource of resources) {
+      content += `- ${resource.serverName}:${resource.uri}`;
+      if (resource.name) {
+        content += ` | ${resource.name}`;
+      }
+      if (resource.description) {
+        content += ` | ${resource.description}`;
+      }
+      content += '\n';
+    }
+
+    return {
+      llmContent: content,
+      returnDisplay: `Listed ${resources.length} resources.`,
+    };
+  }
+}

packages/core/src/tools/mcp-client-manager.test.ts

@@ -821,4 +821,64 @@ describe('McpClientManager', () => {
       expect(coreEventsMock.emitFeedback).toHaveBeenCalledTimes(2); // Now the actual error
     });
   });
+
+  describe('findResourceByUri', () => {
+    it('should find resource by exact URI match', () => {
+      const mockResource = { uri: 'test://resource1', name: 'Resource 1' };
+      const mockResourceRegistry = {
+        getAllResources: vi.fn().mockReturnValue([mockResource]),
+        findResourceByUri: vi.fn(),
+      };
+      mockConfig.getResourceRegistry.mockReturnValue(
+        mockResourceRegistry as unknown as ResourceRegistry,
+      );
+
+      const manager = setupManager(new McpClientManager('0.0.1', mockConfig));
+
+      const result = manager.findResourceByUri('test://resource1');
+      expect(result).toBe(mockResource);
+    });
+
+    it('should try ResourceRegistry.findResourceByUri first', () => {
+      const mockResourceQualified = {
+        uri: 'test://resource1',
+        name: 'Resource 1 Qualified',
+      };
+      const mockResourceDirect = {
+        uri: 'test-server:test://resource1',
+        name: 'Resource 1 Direct',
+      };
+      const mockResourceRegistry = {
+        getAllResources: vi.fn().mockReturnValue([mockResourceDirect]),
+        findResourceByUri: vi.fn().mockReturnValue(mockResourceQualified),
+      };
+      mockConfig.getResourceRegistry.mockReturnValue(
+        mockResourceRegistry as unknown as ResourceRegistry,
+      );
+
+      const manager = setupManager(new McpClientManager('0.0.1', mockConfig));
+
+      const result = manager.findResourceByUri('test-server:test://resource1');
+      expect(result).toBe(mockResourceQualified);
+      expect(mockResourceRegistry.findResourceByUri).toHaveBeenCalledWith(
+        'test-server:test://resource1',
+      );
+      expect(mockResourceRegistry.getAllResources).not.toHaveBeenCalled();
+    });
+
+    it('should return undefined if both fail', () => {
+      const mockResourceRegistry = {
+        getAllResources: vi.fn().mockReturnValue([]),
+        findResourceByUri: vi.fn().mockReturnValue(undefined),
+      };
+      mockConfig.getResourceRegistry.mockReturnValue(
+        mockResourceRegistry as unknown as ResourceRegistry,
+      );
+
+      const manager = setupManager(new McpClientManager('0.0.1', mockConfig));
+
+      const result = manager.findResourceByUri('non-existent');
+      expect(result).toBeUndefined();
+    });
+  });
 });

packages/core/src/tools/mcp-client-manager.ts

@@ -24,7 +24,10 @@ import { debugLogger } from '../utils/debugLogger.js';
 import { createHash } from 'node:crypto';
 import { stableStringify } from '../policy/stable-stringify.js';
 import type { PromptRegistry } from '../prompts/prompt-registry.js';
-import type { ResourceRegistry } from '../resources/resource-registry.js';
+import type {
+  ResourceRegistry,
+  MCPResource,
+} from '../resources/resource-registry.js';
 
 /**
  * Manages the lifecycle of multiple MCP clients, including local child processes.
@@ -161,7 +164,32 @@ export class McpClientManager {
   }
 
   getClient(serverName: string): McpClient | undefined {
-    return this.clients.get(serverName);
+    for (const client of this.clients.values()) {
+      if (client.getServerName() === serverName) {
+        return client;
+      }
+    }
+    return undefined;
+  }
+
+  findResourceByUri(uri: string): MCPResource | undefined {
+    if (!this.mainResourceRegistry) return undefined;
+
+    // Try serverName:uri format first
+    const qualifiedMatch = this.mainResourceRegistry.findResourceByUri(uri);
+    if (qualifiedMatch) {
+      return qualifiedMatch;
+    }
+
+    // Try direct URI match
+    return this.mainResourceRegistry
+      .getAllResources()
+      .find((r) => r.uri === uri);
+  }
+
+  getAllResources(): MCPResource[] {
+    if (!this.mainResourceRegistry) return [];
+    return this.mainResourceRegistry.getAllResources();
   }
 
   removeRegistries(registries: {

packages/core/src/tools/read-mcp-resource.test.ts

@@ -0,0 +1,194 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect, beforeEach, vi, type Mock } from 'vitest';
+import { ReadMcpResourceTool } from './read-mcp-resource.js';
+import { ToolErrorType } from './tool-error.js';
+import type { AgentLoopContext } from '../config/agent-loop-context.js';
+import { createMockMessageBus } from '../test-utils/mock-message-bus.js';
+
+describe('ReadMcpResourceTool', () => {
+  let tool: ReadMcpResourceTool;
+  let mockContext: {
+    config: {
+      getMcpClientManager: Mock;
+    };
+  };
+  let mockMcpManager: {
+    findResourceByUri: Mock;
+    getClient: Mock;
+  };
+  const abortSignal = new AbortController().signal;
+
+  beforeEach(() => {
+    mockMcpManager = {
+      findResourceByUri: vi.fn(),
+      getClient: vi.fn(),
+    };
+
+    mockContext = {
+      config: {
+        getMcpClientManager: vi.fn().mockReturnValue(mockMcpManager),
+      },
+    };
+
+    tool = new ReadMcpResourceTool(
+      mockContext as unknown as AgentLoopContext,
+      createMockMessageBus(),
+    );
+  });
+
+  it('should successfully read a resource', async () => {
+    const uri = 'protocol://resource';
+    const serverName = 'test-server';
+    const resourceName = 'Test Resource';
+    const resourceContent = 'Resource Content';
+
+    mockMcpManager.findResourceByUri.mockReturnValue({
+      uri,
+      serverName,
+      name: resourceName,
+    });
+
+    const mockClient = {
+      readResource: vi.fn().mockResolvedValue({
+        contents: [{ text: resourceContent }],
+      }),
+    };
+    mockMcpManager.getClient.mockReturnValue(mockClient);
+
+    const invocation = (
+      tool as unknown as {
+        createInvocation: (params: Record<string, unknown>) => {
+          getDescription: () => string;
+          execute: (options: { abortSignal: AbortSignal }) => Promise<unknown>;
+        };
+      }
+    ).createInvocation({ uri });
+
+    // Verify description
+    expect(invocation.getDescription()).toBe(
+      `Read MCP resource "${resourceName}" from server "${serverName}"`,
+    );
+
+    const result = (await invocation.execute({ abortSignal })) as {
+      llmContent: string;
+      returnDisplay: string;
+    };
+
+    expect(mockMcpManager.findResourceByUri).toHaveBeenCalledWith(uri);
+    expect(mockMcpManager.getClient).toHaveBeenCalledWith(serverName);
+    expect(mockClient.readResource).toHaveBeenCalledWith(uri);
+    expect(result).toEqual({
+      llmContent: resourceContent + '\n',
+      returnDisplay: `Successfully read resource "${resourceName}" from server "${serverName}"`,
+    });
+  });
+
+  it('should pass raw URI to client when using qualified URI', async () => {
+    const qualifiedUri = 'test-server:protocol://resource';
+    const rawUri = 'protocol://resource';
+    const serverName = 'test-server';
+    const resourceName = 'Test Resource';
+    const resourceContent = 'Resource Content';
+
+    mockMcpManager.findResourceByUri.mockReturnValue({
+      uri: rawUri,
+      serverName,
+      name: resourceName,
+    });
+
+    const mockClient = {
+      readResource: vi.fn().mockResolvedValue({
+        contents: [{ text: resourceContent }],
+      }),
+    };
+    mockMcpManager.getClient.mockReturnValue(mockClient);
+
+    const invocation = (
+      tool as unknown as {
+        createInvocation: (params: Record<string, unknown>) => {
+          execute: (options: { abortSignal: AbortSignal }) => Promise<unknown>;
+        };
+      }
+    ).createInvocation({ uri: qualifiedUri });
+
+    const result = (await invocation.execute({ abortSignal })) as {
+      llmContent: string;
+      returnDisplay: string;
+    };
+
+    expect(mockMcpManager.findResourceByUri).toHaveBeenCalledWith(qualifiedUri);
+    expect(mockMcpManager.getClient).toHaveBeenCalledWith(serverName);
+    expect(mockClient.readResource).toHaveBeenCalledWith(rawUri);
+    expect(result.llmContent).toBe(resourceContent + '\n');
+  });
+
+  it('should return error if MCP Client Manager not available', async () => {
+    mockContext.config.getMcpClientManager.mockReturnValue(undefined);
+
+    const invocation = (
+      tool as unknown as {
+        createInvocation: (params: Record<string, unknown>) => {
+          execute: (options: { abortSignal: AbortSignal }) => Promise<unknown>;
+        };
+      }
+    ).createInvocation({ uri: 'uri' });
+    const result = (await invocation.execute({ abortSignal })) as {
+      error: { type: string; message: string };
+    };
+
+    expect(result.error?.type).toBe(ToolErrorType.EXECUTION_FAILED);
+    expect(result.error?.message).toContain('MCP Client Manager not available');
+  });
+
+  it('should return error if resource not found', async () => {
+    mockMcpManager.findResourceByUri.mockReturnValue(undefined);
+
+    const invocation = (
+      tool as unknown as {
+        createInvocation: (params: Record<string, unknown>) => {
+          execute: (options: { abortSignal: AbortSignal }) => Promise<unknown>;
+        };
+      }
+    ).createInvocation({ uri: 'uri' });
+    const result = (await invocation.execute({ abortSignal })) as {
+      error: { type: string; message: string };
+    };
+
+    expect(result.error?.type).toBe(ToolErrorType.MCP_RESOURCE_NOT_FOUND);
+    expect(result.error?.message).toContain('Resource not found');
+  });
+
+  it('should return error if reading fails', async () => {
+    const uri = 'protocol://resource';
+    const serverName = 'test-server';
+
+    mockMcpManager.findResourceByUri.mockReturnValue({
+      uri,
+      serverName,
+    });
+
+    const mockClient = {
+      readResource: vi.fn().mockRejectedValue(new Error('Failed to read')),
+    };
+    mockMcpManager.getClient.mockReturnValue(mockClient);
+
+    const invocation = (
+      tool as unknown as {
+        createInvocation: (params: Record<string, unknown>) => {
+          execute: (options: { abortSignal: AbortSignal }) => Promise<unknown>;
+        };
+      }
+    ).createInvocation({ uri });
+    const result = (await invocation.execute({ abortSignal })) as {
+      error: { type: string; message: string };
+    };
+
+    expect(result.error?.type).toBe(ToolErrorType.MCP_TOOL_ERROR);
+    expect(result.error?.message).toContain('Failed to read resource');
+  });
+});

packages/core/src/tools/read-mcp-resource.ts

@@ -0,0 +1,169 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import {
+  BaseDeclarativeTool,
+  BaseToolInvocation,
+  Kind,
+  type ToolResult,
+  type ExecuteOptions,
+} from './tools.js';
+import type { MessageBus } from '../confirmation-bus/message-bus.js';
+import { READ_MCP_RESOURCE_TOOL_NAME } from './tool-names.js';
+import { READ_MCP_RESOURCE_DEFINITION } from './definitions/coreTools.js';
+import type { AgentLoopContext } from '../config/agent-loop-context.js';
+import { ToolErrorType } from './tool-error.js';
+import type { MCPResource } from '../resources/resource-registry.js';
+
+export interface ReadMcpResourceParams {
+  uri: string;
+}
+
+export class ReadMcpResourceTool extends BaseDeclarativeTool<
+  ReadMcpResourceParams,
+  ToolResult
+> {
+  static readonly Name = READ_MCP_RESOURCE_TOOL_NAME;
+
+  constructor(
+    private readonly context: AgentLoopContext,
+    messageBus: MessageBus,
+  ) {
+    super(
+      ReadMcpResourceTool.Name,
+      'Read MCP Resource',
+      READ_MCP_RESOURCE_DEFINITION.base.description!,
+      Kind.Read,
+      READ_MCP_RESOURCE_DEFINITION.base.parametersJsonSchema,
+      messageBus,
+      true,
+      false,
+    );
+  }
+
+  protected createInvocation(
+    params: ReadMcpResourceParams,
+  ): ReadMcpResourceToolInvocation {
+    return new ReadMcpResourceToolInvocation(
+      this.context,
+      params,
+      this.messageBus,
+    );
+  }
+}
+
+class ReadMcpResourceToolInvocation extends BaseToolInvocation<
+  ReadMcpResourceParams,
+  ToolResult
+> {
+  private resource: MCPResource | undefined;
+
+  constructor(
+    private readonly context: AgentLoopContext,
+    params: ReadMcpResourceParams,
+    messageBus: MessageBus,
+  ) {
+    super(params, messageBus, ReadMcpResourceTool.Name, 'Read MCP Resource');
+    const mcpManager = this.context.config.getMcpClientManager();
+    this.resource = mcpManager?.findResourceByUri(params.uri);
+  }
+
+  getDescription(): string {
+    if (this.resource) {
+      return `Read MCP resource "${this.resource.name}" from server "${this.resource.serverName}"`;
+    }
+    return `Read MCP resource: ${this.params.uri}`;
+  }
+
+  async execute({
+    abortSignal: _abortSignal,
+  }: ExecuteOptions): Promise<ToolResult> {
+    const mcpManager = this.context.config.getMcpClientManager();
+    if (!mcpManager) {
+      return {
+        llmContent: 'Error: MCP Client Manager not available.',
+        returnDisplay: 'Error: MCP Client Manager not available.',
+        error: {
+          message: 'MCP Client Manager not available.',
+          type: ToolErrorType.EXECUTION_FAILED,
+        },
+      };
+    }
+
+    const uri = this.params.uri;
+    if (!uri) {
+      return {
+        llmContent: 'Error: No URI provided.',
+        returnDisplay: 'Error: No URI provided.',
+        error: {
+          message: 'No URI provided.',
+          type: ToolErrorType.INVALID_TOOL_PARAMS,
+        },
+      };
+    }
+
+    const resource = mcpManager.findResourceByUri(uri);
+    if (!resource) {
+      const errorMessage = `Resource not found for URI: ${uri}`;
+      return {
+        llmContent: `Error: ${errorMessage}`,
+        returnDisplay: `Error: ${errorMessage}`,
+        error: {
+          message: errorMessage,
+          type: ToolErrorType.MCP_RESOURCE_NOT_FOUND,
+        },
+      };
+    }
+
+    const client = mcpManager.getClient(resource.serverName);
+    if (!client) {
+      const errorMessage = `MCP Client not found for server: ${resource.serverName}`;
+      return {
+        llmContent: `Error: ${errorMessage}`,
+        returnDisplay: `Error: ${errorMessage}`,
+        error: {
+          message: errorMessage,
+          type: ToolErrorType.EXECUTION_FAILED,
+        },
+      };
+    }
+
+    try {
+      const result = await client.readResource(resource.uri);
+      // The result should contain contents.
+      // Let's assume it returns a string or an object with contents.
+      // According to MCP spec, it returns { contents: [...] }.
+      // We should format it nicely.
+      let contentText = '';
+      if (result && result.contents) {
+        for (const content of result.contents) {
+          if ('text' in content && content.text) {
+            contentText += content.text + '\n';
+          } else if ('blob' in content && content.blob) {
+            contentText += `[Binary Data (${content.mimeType})]` + '\n';
+          }
+        }
+      }
+
+      return {
+        llmContent: contentText || 'No content returned from resource.',
+        returnDisplay: this.resource
+          ? `Successfully read resource "${this.resource.name}" from server "${this.resource.serverName}"`
+          : `Successfully read resource: ${uri}`,
+      };
+    } catch (e) {
+      const errorMessage = `Failed to read resource: ${e instanceof Error ? e.message : String(e)}`;
+      return {
+        llmContent: `Error: ${errorMessage}`,
+        returnDisplay: `Error: ${errorMessage}`,
+        error: {
+          message: errorMessage,
+          type: ToolErrorType.MCP_TOOL_ERROR,
+        },
+      };
+    }
+  }
+}

packages/core/src/tools/tool-error.ts

@@ -55,6 +55,7 @@ export enum ToolErrorType {
 
   // MCP-specific Errors
   MCP_TOOL_ERROR = 'mcp_tool_error',
+  MCP_RESOURCE_NOT_FOUND = 'mcp_resource_not_found',
 
   // Memory-specific Errors
   MEMORY_TOOL_EXECUTION_ERROR = 'memory_tool_execution_error',

packages/core/src/tools/tool-names.ts

@@ -79,6 +79,8 @@ import {
   UPDATE_TOPIC_DISPLAY_NAME,
   COMPLETE_TASK_TOOL_NAME,
   COMPLETE_TASK_DISPLAY_NAME,
+  READ_MCP_RESOURCE_TOOL_NAME,
+  LIST_MCP_RESOURCES_TOOL_NAME,
   TOPIC_PARAM_TITLE,
   TOPIC_PARAM_SUMMARY,
   TOPIC_PARAM_STRATEGIC_INTENT,
@@ -106,6 +108,8 @@ export {
   UPDATE_TOPIC_DISPLAY_NAME,
   COMPLETE_TASK_TOOL_NAME,
   COMPLETE_TASK_DISPLAY_NAME,
+  READ_MCP_RESOURCE_TOOL_NAME,
+  LIST_MCP_RESOURCES_TOOL_NAME,
   // Shared parameter names
   PARAM_FILE_PATH,
   PARAM_DIR_PATH,
@@ -272,6 +276,8 @@ export const ALL_BUILTIN_TOOL_NAMES = [
   UPDATE_TOPIC_TOOL_NAME,
   COMPLETE_TASK_TOOL_NAME,
   AGENT_TOOL_NAME,
+  READ_MCP_RESOURCE_TOOL_NAME,
+  LIST_MCP_RESOURCES_TOOL_NAME,
 ] as const;
 
 /**
@@ -291,6 +297,8 @@ export const PLAN_MODE_TOOLS = [
   UPDATE_TOPIC_TOOL_NAME,
   'codebase_investigator',
   'cli_help',
+  READ_MCP_RESOURCE_TOOL_NAME,
+  LIST_MCP_RESOURCES_TOOL_NAME,
 ] as const;
 
 /**

packages/core/src/tools/tool-registry.ts

@@ -34,6 +34,8 @@ import {
   UPDATE_TOPIC_TOOL_NAME,
   ENTER_PLAN_MODE_TOOL_NAME,
   EXIT_PLAN_MODE_TOOL_NAME,
+  READ_MCP_RESOURCE_TOOL_NAME,
+  LIST_MCP_RESOURCES_TOOL_NAME,
 } from './tool-names.js';
 
 type ToolParams = Record<string, unknown>;
@@ -602,6 +604,16 @@ export class ToolRegistry {
       }
     }
 
+    if (
+      tool.name === READ_MCP_RESOURCE_TOOL_NAME ||
+      tool.name === LIST_MCP_RESOURCES_TOOL_NAME
+    ) {
+      const mcpManager = this.config.getMcpClientManager();
+      if (!mcpManager || mcpManager.getAllResources().length === 0) {
+        return false;
+      }
+    }
+
     const isPlanMode = this.config.getApprovalMode() === ApprovalMode.PLAN;
     if (
       (tool.name === ENTER_PLAN_MODE_TOOL_NAME && isPlanMode) ||