feat(MCP Client Tool Node): Add MCP Client Tool Node to connect to MCP servers over SSE (#14464)

Co-authored-by: कारतोफ्फेलस्क्रिप्ट™ <aditya@netroy.in>
Co-authored-by: JP van Oosten <jp@n8n.io>

packages/@n8n/nodes-langchain/nodes/mcp/McpClientTool/McpClientTool.node.test.ts

@@ -0,0 +1,287 @@
+import { Client } from '@modelcontextprotocol/sdk/client/index.js';
+import { SSEClientTransport } from '@modelcontextprotocol/sdk/client/sse.js';
+import { mock } from 'jest-mock-extended';
+import {
+	NodeOperationError,
+	type ILoadOptionsFunctions,
+	type INode,
+	type ISupplyDataFunctions,
+} from 'n8n-workflow';
+
+import { getTools } from './loadOptions';
+import { McpClientTool } from './McpClientTool.node';
+import { McpToolkit } from './utils';
+
+jest.mock('@modelcontextprotocol/sdk/client/sse.js');
+jest.mock('@modelcontextprotocol/sdk/client/index.js');
+
+describe('McpClientTool', () => {
+	describe('loadOptions: getTools', () => {
+		it('should return a list of tools', async () => {
+			jest.spyOn(Client.prototype, 'connect').mockResolvedValue();
+			jest.spyOn(Client.prototype, 'listTools').mockResolvedValue({
+				tools: [
+					{
+						name: 'MyTool',
+						description: 'MyTool does something',
+						inputSchema: { type: 'object', properties: { input: { type: 'string' } } },
+					},
+				],
+			});
+
+			const result = await getTools.call(
+				mock<ILoadOptionsFunctions>({ getNode: jest.fn(() => mock<INode>({ typeVersion: 1 })) }),
+			);
+
+			expect(result).toEqual([
+				{
+					description: 'MyTool does something',
+					name: 'MyTool',
+					value: 'MyTool',
+				},
+			]);
+		});
+
+		it('should handle errors', async () => {
+			jest.spyOn(Client.prototype, 'connect').mockRejectedValue(new Error('Fail!'));
+
+			const node = mock<INode>({ typeVersion: 1 });
+			await expect(
+				getTools.call(mock<ILoadOptionsFunctions>({ getNode: jest.fn(() => node) })),
+			).rejects.toEqual(new NodeOperationError(node, 'Could not connect to your MCP server'));
+		});
+	});
+
+	describe('supplyData', () => {
+		beforeEach(() => {
+			jest.resetAllMocks();
+		});
+
+		it('should return a valid toolkit with usable tools', async () => {
+			jest.spyOn(Client.prototype, 'connect').mockResolvedValue();
+			jest
+				.spyOn(Client.prototype, 'callTool')
+				.mockResolvedValue({ content: [{ type: 'text', text: 'result from tool' }] });
+			jest.spyOn(Client.prototype, 'listTools').mockResolvedValue({
+				tools: [
+					{
+						name: 'MyTool1',
+						description: 'MyTool1 does something',
+						inputSchema: { type: 'object', properties: { input: { type: 'string' } } },
+					},
+					{
+						name: 'MyTool2',
+						description: 'MyTool2 does something',
+						inputSchema: { type: 'object', properties: { input2: { type: 'string' } } },
+					},
+				],
+			});
+
+			const supplyDataResult = await new McpClientTool().supplyData.call(
+				mock<ISupplyDataFunctions>({
+					getNode: jest.fn(() => mock<INode>({ typeVersion: 1 })),
+					logger: { debug: jest.fn(), error: jest.fn() },
+					addInputData: jest.fn(() => ({ index: 0 })),
+				}),
+				0,
+			);
+
+			expect(supplyDataResult.closeFunction).toBeInstanceOf(Function);
+			expect(supplyDataResult.response).toBeInstanceOf(McpToolkit);
+
+			const tools = (supplyDataResult.response as McpToolkit).getTools();
+			expect(tools).toHaveLength(2);
+
+			const toolCallResult = await tools[0].invoke({ input: 'foo' });
+			expect(toolCallResult).toEqual([{ type: 'text', text: 'result from tool' }]);
+		});
+
+		it('should support selecting tools to expose', async () => {
+			jest.spyOn(Client.prototype, 'connect').mockResolvedValue();
+			jest.spyOn(Client.prototype, 'listTools').mockResolvedValue({
+				tools: [
+					{
+						name: 'MyTool1',
+						description: 'MyTool1 does something',
+						inputSchema: { type: 'object', properties: { input: { type: 'string' } } },
+					},
+					{
+						name: 'MyTool2',
+						description: 'MyTool2 does something',
+						inputSchema: { type: 'object', properties: { input2: { type: 'string' } } },
+					},
+				],
+			});
+
+			const supplyDataResult = await new McpClientTool().supplyData.call(
+				mock<ISupplyDataFunctions>({
+					getNode: jest.fn(() =>
+						mock<INode>({
+							typeVersion: 1,
+						}),
+					),
+					getNodeParameter: jest.fn((key, _index) => {
+						const parameters: Record<string, any> = {
+							include: 'selected',
+							includeTools: ['MyTool2'],
+						};
+						return parameters[key];
+					}),
+					logger: { debug: jest.fn(), error: jest.fn() },
+					addInputData: jest.fn(() => ({ index: 0 })),
+				}),
+				0,
+			);
+
+			expect(supplyDataResult.closeFunction).toBeInstanceOf(Function);
+			expect(supplyDataResult.response).toBeInstanceOf(McpToolkit);
+
+			const tools = (supplyDataResult.response as McpToolkit).getTools();
+			expect(tools).toHaveLength(1);
+			expect(tools[0].name).toBe('MyTool2');
+		});
+
+		it('should support selecting tools to exclude', async () => {
+			jest.spyOn(Client.prototype, 'connect').mockResolvedValue();
+			jest.spyOn(Client.prototype, 'listTools').mockResolvedValue({
+				tools: [
+					{
+						name: 'MyTool1',
+						description: 'MyTool1 does something',
+						inputSchema: { type: 'object', properties: { input: { type: 'string' } } },
+					},
+					{
+						name: 'MyTool2',
+						description: 'MyTool2 does something',
+						inputSchema: { type: 'object', properties: { input2: { type: 'string' } } },
+					},
+				],
+			});
+
+			const supplyDataResult = await new McpClientTool().supplyData.call(
+				mock<ISupplyDataFunctions>({
+					getNode: jest.fn(() =>
+						mock<INode>({
+							typeVersion: 1,
+						}),
+					),
+					getNodeParameter: jest.fn((key, _index) => {
+						const parameters: Record<string, any> = {
+							include: 'except',
+							excludeTools: ['MyTool2'],
+						};
+						return parameters[key];
+					}),
+					logger: { debug: jest.fn(), error: jest.fn() },
+					addInputData: jest.fn(() => ({ index: 0 })),
+				}),
+				0,
+			);
+
+			expect(supplyDataResult.closeFunction).toBeInstanceOf(Function);
+			expect(supplyDataResult.response).toBeInstanceOf(McpToolkit);
+
+			const tools = (supplyDataResult.response as McpToolkit).getTools();
+			expect(tools).toHaveLength(1);
+			expect(tools[0].name).toBe('MyTool1');
+		});
+
+		it('should support header auth', async () => {
+			jest.spyOn(Client.prototype, 'connect').mockResolvedValue();
+			jest.spyOn(Client.prototype, 'listTools').mockResolvedValue({
+				tools: [
+					{
+						name: 'MyTool1',
+						description: 'MyTool1 does something',
+						inputSchema: { type: 'object', properties: { input: { type: 'string' } } },
+					},
+				],
+			});
+
+			const supplyDataResult = await new McpClientTool().supplyData.call(
+				mock<ISupplyDataFunctions>({
+					getNode: jest.fn(() => mock<INode>({ typeVersion: 1 })),
+					getNodeParameter: jest.fn((key, _index) => {
+						const parameters: Record<string, any> = {
+							include: 'except',
+							excludeTools: ['MyTool2'],
+							authentication: 'headerAuth',
+							sseEndpoint: 'https://my-mcp-endpoint.ai/sse',
+						};
+						return parameters[key];
+					}),
+					logger: { debug: jest.fn(), error: jest.fn() },
+					addInputData: jest.fn(() => ({ index: 0 })),
+					getCredentials: jest.fn().mockResolvedValue({ name: 'my-header', value: 'header-value' }),
+				}),
+				0,
+			);
+
+			expect(supplyDataResult.closeFunction).toBeInstanceOf(Function);
+			expect(supplyDataResult.response).toBeInstanceOf(McpToolkit);
+
+			const fetchSpy = jest.spyOn(global, 'fetch').mockResolvedValue(mock());
+			const url = new URL('https://my-mcp-endpoint.ai/sse');
+			expect(SSEClientTransport).toHaveBeenCalledTimes(1);
+			expect(SSEClientTransport).toHaveBeenCalledWith(url, {
+				eventSourceInit: { fetch: expect.any(Function) },
+				requestInit: { headers: { 'my-header': 'header-value' } },
+			});
+
+			const customFetch = jest.mocked(SSEClientTransport).mock.calls[0][1]?.eventSourceInit?.fetch;
+			await customFetch?.(url);
+			expect(fetchSpy).toHaveBeenCalledWith(url, {
+				headers: { Accept: 'text/event-stream', 'my-header': 'header-value' },
+			});
+		});
+
+		it('should support bearer auth', async () => {
+			jest.spyOn(Client.prototype, 'connect').mockResolvedValue();
+			jest.spyOn(Client.prototype, 'listTools').mockResolvedValue({
+				tools: [
+					{
+						name: 'MyTool1',
+						description: 'MyTool1 does something',
+						inputSchema: { type: 'object', properties: { input: { type: 'string' } } },
+					},
+				],
+			});
+
+			const supplyDataResult = await new McpClientTool().supplyData.call(
+				mock<ISupplyDataFunctions>({
+					getNode: jest.fn(() => mock<INode>({ typeVersion: 1 })),
+					getNodeParameter: jest.fn((key, _index) => {
+						const parameters: Record<string, any> = {
+							include: 'except',
+							excludeTools: ['MyTool2'],
+							authentication: 'bearerAuth',
+							sseEndpoint: 'https://my-mcp-endpoint.ai/sse',
+						};
+						return parameters[key];
+					}),
+					logger: { debug: jest.fn(), error: jest.fn() },
+					addInputData: jest.fn(() => ({ index: 0 })),
+					getCredentials: jest.fn().mockResolvedValue({ token: 'my-token' }),
+				}),
+				0,
+			);
+
+			expect(supplyDataResult.closeFunction).toBeInstanceOf(Function);
+			expect(supplyDataResult.response).toBeInstanceOf(McpToolkit);
+
+			const fetchSpy = jest.spyOn(global, 'fetch').mockResolvedValue(mock());
+			const url = new URL('https://my-mcp-endpoint.ai/sse');
+			expect(SSEClientTransport).toHaveBeenCalledTimes(1);
+			expect(SSEClientTransport).toHaveBeenCalledWith(url, {
+				eventSourceInit: { fetch: expect.any(Function) },
+				requestInit: { headers: { Authorization: 'Bearer my-token' } },
+			});
+
+			const customFetch = jest.mocked(SSEClientTransport).mock.calls[0][1]?.eventSourceInit?.fetch;
+			await customFetch?.(url);
+			expect(fetchSpy).toHaveBeenCalledWith(url, {
+				headers: { Accept: 'text/event-stream', Authorization: 'Bearer my-token' },
+			});
+		});
+	});
+});

packages/@n8n/nodes-langchain/nodes/mcp/McpClientTool/McpClientTool.node.ts

@@ -0,0 +1,262 @@
+import {
+	NodeConnectionTypes,
+	NodeOperationError,
+	type INodeType,
+	type INodeTypeDescription,
+	type ISupplyDataFunctions,
+	type SupplyData,
+} from 'n8n-workflow';
+
+import { logWrapper } from '@utils/logWrapper';
+import { getConnectionHintNoticeField } from '@utils/sharedFields';
+
+import { getTools } from './loadOptions';
+import type { McpAuthenticationOption, McpToolIncludeMode } from './types';
+import {
+	connectMcpClient,
+	createCallTool,
+	getAllTools,
+	getAuthHeaders,
+	getSelectedTools,
+	McpToolkit,
+	mcpToolToDynamicTool,
+} from './utils';
+
+export class McpClientTool implements INodeType {
+	description: INodeTypeDescription = {
+		displayName: 'MCP Client Tool',
+		name: 'mcpClientTool',
+		icon: {
+			light: 'file:../mcp.svg',
+			dark: 'file:../mcp.dark.svg',
+		},
+		group: ['output'],
+		version: 1,
+		description: 'Connect tools from an MCP Server',
+		defaults: {
+			name: 'MCP Client',
+		},
+		codex: {
+			categories: ['AI'],
+			subcategories: {
+				AI: ['Model Context Protocol', 'Tools'],
+			},
+			alias: ['Model Context Protocol', 'MCP Client'],
+			resources: {
+				primaryDocumentation: [
+					{
+						url: 'https://docs.n8n.io/integrations/builtin/cluster-nodes/sub-nodes/n8n-nodes-langchain.mcpclienttool/',
+					},
+				],
+			},
+		},
+		inputs: [],
+		outputs: [{ type: NodeConnectionTypes.AiTool, displayName: 'Tools' }],
+		credentials: [
+			{
+				// eslint-disable-next-line n8n-nodes-base/node-class-description-credentials-name-unsuffixed
+				name: 'httpBearerAuth',
+				required: true,
+				displayOptions: {
+					show: {
+						authentication: ['bearerAuth'],
+					},
+				},
+			},
+			{
+				name: 'httpHeaderAuth',
+				required: true,
+				displayOptions: {
+					show: {
+						authentication: ['headerAuth'],
+					},
+				},
+			},
+		],
+		properties: [
+			getConnectionHintNoticeField([NodeConnectionTypes.AiAgent]),
+			{
+				displayName: 'SSE Endpoint',
+				name: 'sseEndpoint',
+				type: 'string',
+				description: 'SSE Endpoint of your MCP server',
+				placeholder: 'e.g. https://my-mcp-server.ai/sse',
+				default: '',
+				required: true,
+			},
+			{
+				displayName: 'Authentication',
+				name: 'authentication',
+				type: 'options',
+				options: [
+					{
+						name: 'Bearer Auth',
+						value: 'bearerAuth',
+					},
+					{
+						name: 'Header Auth',
+						value: 'headerAuth',
+					},
+					{
+						name: 'None',
+						value: 'none',
+					},
+				],
+				default: 'none',
+				description: 'The way to authenticate with your SSE endpoint',
+			},
+			{
+				displayName: 'Credentials',
+				name: 'credentials',
+				type: 'credentials',
+				default: '',
+				displayOptions: {
+					show: {
+						authentication: ['headerAuth', 'bearerAuth'],
+					},
+				},
+			},
+			{
+				displayName: 'Tools to Include',
+				name: 'include',
+				type: 'options',
+				description: 'How to select the tools you want to be exposed to the AI Agent',
+				default: 'all',
+				options: [
+					{
+						name: 'All',
+						value: 'all',
+						description: 'Also include all unchanged fields from the input',
+					},
+					{
+						name: 'Selected',
+						value: 'selected',
+						description: 'Also include the tools listed in the parameter "Tools to Include"',
+					},
+					{
+						name: 'All Except',
+						value: 'except',
+						description: 'Exclude the tools listed in the parameter "Tools to Exclude"',
+					},
+				],
+			},
+			{
+				displayName: 'Tools to Include',
+				name: 'includeTools',
+				type: 'multiOptions',
+				default: [],
+				description:
+					'Choose from the list, or specify IDs using an <a href="https://docs.n8n.io/code/expressions/">expression</a>',
+				typeOptions: {
+					loadOptionsMethod: 'getTools',
+					loadOptionsDependsOn: ['sseEndpoint'],
+				},
+				displayOptions: {
+					show: {
+						include: ['selected'],
+					},
+				},
+			},
+			{
+				displayName: 'Tools to Exclude',
+				name: 'excludeTools',
+				type: 'multiOptions',
+				default: [],
+				description:
+					'Choose from the list, or specify IDs using an <a href="https://docs.n8n.io/code/expressions/">expression</a>',
+				typeOptions: {
+					loadOptionsMethod: 'getTools',
+				},
+				displayOptions: {
+					show: {
+						include: ['except'],
+					},
+				},
+			},
+		],
+	};
+
+	methods = {
+		loadOptions: {
+			getTools,
+		},
+	};
+
+	async supplyData(this: ISupplyDataFunctions, itemIndex: number): Promise<SupplyData> {
+		const authentication = this.getNodeParameter(
+			'authentication',
+			itemIndex,
+		) as McpAuthenticationOption;
+		const sseEndpoint = this.getNodeParameter('sseEndpoint', itemIndex) as string;
+		const node = this.getNode();
+		const { headers } = await getAuthHeaders(this, authentication);
+		const client = await connectMcpClient({
+			sseEndpoint,
+			headers,
+			name: node.type,
+			version: node.typeVersion,
+		});
+
+		const setError = (message: string, description?: string): SupplyData => {
+			const error = new NodeOperationError(node, message, { itemIndex, description });
+			this.addOutputData(NodeConnectionTypes.AiTool, itemIndex, error);
+			throw error;
+		};
+
+		if (!client.ok) {
+			this.logger.error('McpClientTool: Failed to connect to MCP Server', {
+				error: client.error,
+			});
+
+			switch (client.error.type) {
+				case 'invalid_url':
+					return setError('Could not connect to your MCP server. The provided URL is invalid.');
+				case 'connection':
+				default:
+					return setError('Could not connect to your MCP server');
+			}
+		}
+
+		this.logger.debug('McpClientTool: Successfully connected to MCP Server');
+
+		const mode = this.getNodeParameter('include', itemIndex) as McpToolIncludeMode;
+		const includeTools = this.getNodeParameter('includeTools', itemIndex, []) as string[];
+		const excludeTools = this.getNodeParameter('excludeTools', itemIndex, []) as string[];
+
+		const allTools = await getAllTools(client.result);
+		const mcpTools = getSelectedTools({
+			tools: allTools,
+			mode,
+			includeTools,
+			excludeTools,
+		});
+
+		if (!mcpTools.length) {
+			return setError(
+				'MCP Server returned no tools',
+				'Connected successfully to your MCP server but it returned an empty list of tools.',
+			);
+		}
+
+		const tools = mcpTools.map((tool) =>
+			logWrapper(
+				mcpToolToDynamicTool(
+					tool,
+					createCallTool(tool.name, client.result, (error) => {
+						this.logger.error(`McpClientTool: Tool "${tool.name}" failed to execute`, { error });
+						throw new NodeOperationError(node, `Failed to execute tool "${tool.name}"`, {
+							description: error,
+						});
+					}),
+				),
+				this,
+			),
+		);
+
+		this.logger.debug(`McpClientTool: Connected to MCP Server with ${tools.length} tools`);
+
+		const toolkit = new McpToolkit(tools);
+
+		return { response: toolkit, closeFunction: async () => await client.result.close() };
+	}
+}

packages/@n8n/nodes-langchain/nodes/mcp/McpClientTool/loadOptions.ts

@@ -0,0 +1,32 @@
+import {
+	type ILoadOptionsFunctions,
+	type INodePropertyOptions,
+	NodeOperationError,
+} from 'n8n-workflow';
+
+import type { McpAuthenticationOption } from './types';
+import { connectMcpClient, getAllTools, getAuthHeaders } from './utils';
+
+export async function getTools(this: ILoadOptionsFunctions): Promise<INodePropertyOptions[]> {
+	const authentication = this.getNodeParameter('authentication') as McpAuthenticationOption;
+	const sseEndpoint = this.getNodeParameter('sseEndpoint') as string;
+	const node = this.getNode();
+	const { headers } = await getAuthHeaders(this, authentication);
+	const client = await connectMcpClient({
+		sseEndpoint,
+		headers,
+		name: node.type,
+		version: node.typeVersion,
+	});
+
+	if (!client.ok) {
+		throw new NodeOperationError(this.getNode(), 'Could not connect to your MCP server');
+	}
+
+	const tools = await getAllTools(client.result);
+	return tools.map((tool) => ({
+		name: tool.name,
+		value: tool.name,
+		description: tool.description,
+	}));
+}

packages/@n8n/nodes-langchain/nodes/mcp/McpClientTool/types.ts

@@ -0,0 +1,7 @@
+import type { JSONSchema7 } from 'json-schema';
+
+export type McpTool = { name: string; description?: string; inputSchema: JSONSchema7 };
+
+export type McpToolIncludeMode = 'all' | 'selected' | 'except';
+
+export type McpAuthenticationOption = 'none' | 'headerAuth' | 'bearerAuth';

packages/@n8n/nodes-langchain/nodes/mcp/McpClientTool/utils.ts

@@ -0,0 +1,212 @@
+import { Client } from '@modelcontextprotocol/sdk/client/index.js';
+import { SSEClientTransport } from '@modelcontextprotocol/sdk/client/sse.js';
+import { CompatibilityCallToolResultSchema } from '@modelcontextprotocol/sdk/types.js';
+import { Toolkit } from 'langchain/agents';
+import { DynamicStructuredTool, type DynamicStructuredToolInput } from 'langchain/tools';
+import {
+	createResultError,
+	createResultOk,
+	type IDataObject,
+	type IExecuteFunctions,
+	type Result,
+} from 'n8n-workflow';
+import { type ZodTypeAny } from 'zod';
+
+import { convertJsonSchemaToZod } from '@utils/schemaParsing';
+
+import type { McpAuthenticationOption, McpTool, McpToolIncludeMode } from './types';
+
+export async function getAllTools(client: Client, cursor?: string): Promise<McpTool[]> {
+	const { tools, nextCursor } = await client.listTools({ cursor });
+
+	if (nextCursor) {
+		return (tools as McpTool[]).concat(await getAllTools(client, nextCursor));
+	}
+
+	return tools as McpTool[];
+}
+
+export function getSelectedTools({
+	mode,
+	includeTools,
+	excludeTools,
+	tools,
+}: {
+	mode: McpToolIncludeMode;
+	includeTools?: string[];
+	excludeTools?: string[];
+	tools: McpTool[];
+}) {
+	switch (mode) {
+		case 'selected': {
+			if (!includeTools?.length) return tools;
+			const include = new Set(includeTools);
+			return tools.filter((tool) => include.has(tool.name));
+		}
+		case 'except': {
+			const except = new Set(excludeTools ?? []);
+			return tools.filter((tool) => !except.has(tool.name));
+		}
+		case 'all':
+		default:
+			return tools;
+	}
+}
+
+export const getErrorDescriptionFromToolCall = (result: unknown): string | undefined => {
+	if (result && typeof result === 'object') {
+		if ('content' in result && Array.isArray(result.content)) {
+			const errorMessage = (result.content as Array<{ type: 'text'; text: string }>).find(
+				(content) => content && typeof content === 'object' && typeof content.text === 'string',
+			)?.text;
+			return errorMessage;
+		} else if ('toolResult' in result && typeof result.toolResult === 'string') {
+			return result.toolResult;
+		}
+		if ('message' in result && typeof result.message === 'string') {
+			return result.message;
+		}
+	}
+
+	return undefined;
+};
+
+export const createCallTool =
+	(name: string, client: Client, onError: (error: string | undefined) => void) =>
+	async (args: IDataObject) => {
+		let result: Awaited<ReturnType<Client['callTool']>>;
+		try {
+			result = await client.callTool({ name, arguments: args }, CompatibilityCallToolResultSchema);
+		} catch (error) {
+			return onError(getErrorDescriptionFromToolCall(error));
+		}
+
+		if (result.isError) {
+			return onError(getErrorDescriptionFromToolCall(result));
+		}
+
+		if (result.toolResult !== undefined) {
+			return result.toolResult;
+		}
+
+		if (result.content !== undefined) {
+			return result.content;
+		}
+
+		return result;
+	};
+
+export function mcpToolToDynamicTool(
+	tool: McpTool,
+	onCallTool: DynamicStructuredToolInput['func'],
+) {
+	return new DynamicStructuredTool({
+		name: tool.name,
+		description: tool.description ?? '',
+		schema: convertJsonSchemaToZod(tool.inputSchema),
+		func: onCallTool,
+		metadata: { isFromToolkit: true },
+	});
+}
+
+export class McpToolkit extends Toolkit {
+	constructor(public tools: Array<DynamicStructuredTool<ZodTypeAny>>) {
+		super();
+	}
+}
+
+function safeCreateUrl(url: string, baseUrl?: string | URL): Result<URL, Error> {
+	try {
+		return createResultOk(new URL(url, baseUrl));
+	} catch (error) {
+		return createResultError(error);
+	}
+}
+
+function normalizeAndValidateUrl(input: string): Result<URL, Error> {
+	const withProtocol = !/^https?:\/\//i.test(input) ? `https://${input}` : input;
+	const parsedUrl = safeCreateUrl(withProtocol);
+
+	if (!parsedUrl.ok) {
+		return createResultError(parsedUrl.error);
+	}
+
+	return parsedUrl;
+}
+
+type ConnectMcpClientError =
+	| { type: 'invalid_url'; error: Error }
+	| { type: 'connection'; error: Error };
+export async function connectMcpClient({
+	headers,
+	sseEndpoint,
+	name,
+	version,
+}: {
+	sseEndpoint: string;
+	headers?: Record<string, string>;
+	name: string;
+	version: number;
+}): Promise<Result<Client, ConnectMcpClientError>> {
+	try {
+		const endpoint = normalizeAndValidateUrl(sseEndpoint);
+
+		if (!endpoint.ok) {
+			return createResultError({ type: 'invalid_url', error: endpoint.error });
+		}
+
+		const transport = new SSEClientTransport(endpoint.result, {
+			eventSourceInit: {
+				fetch: async (url, init) =>
+					await fetch(url, {
+						...init,
+						headers: {
+							...headers,
+							Accept: 'text/event-stream',
+						},
+					}),
+			},
+			requestInit: { headers },
+		});
+
+		const client = new Client(
+			{ name, version: version.toString() },
+			{ capabilities: { tools: {} } },
+		);
+
+		await client.connect(transport);
+		return createResultOk(client);
+	} catch (error) {
+		return createResultError({ type: 'connection', error });
+	}
+}
+
+export async function getAuthHeaders(
+	ctx: Pick<IExecuteFunctions, 'getCredentials'>,
+	authentication: McpAuthenticationOption,
+): Promise<{ headers?: Record<string, string> }> {
+	switch (authentication) {
+		case 'headerAuth': {
+			const header = await ctx
+				.getCredentials<{ name: string; value: string }>('httpHeaderAuth')
+				.catch(() => null);
+
+			if (!header) return {};
+
+			return { headers: { [header.name]: header.value } };
+		}
+		case 'bearerAuth': {
+			const result = await ctx
+				.getCredentials<{ token: string }>('httpBearerAuth')
+				.catch(() => null);
+
+			if (!result) return {};
+
+			return { headers: { Authorization: `Bearer ${result.token}` } };
+		}
+		case 'none':
+		default: {
+			return {};
+		}
+	}
+}

packages/@n8n/nodes-langchain/nodes/mcp/McpTrigger/McpServer.ts

@@ -148,8 +148,13 @@ export class McpServer {
 
 				this.logger.debug(`Got request for ${requestedTool.name}, and executed it.`);
 
-				// TODO: Refactor this to no longer use the legacy tool result, but
+				if (typeof result === 'object') {
-				return { toolResult: result };
+					return { content: [{ type: 'text', text: JSON.stringify(result) }] };
+				}
+				if (typeof result === 'string') {
+					return { content: [{ type: 'text', text: result }] };
+				}
+				return { content: [{ type: 'text', text: String(result) }] };
 			} catch (error) {
 				this.logger.error(`Error while executing Tool ${requestedTool.name}: ${error}`);
 				return { isError: true, content: [{ type: 'text', text: `Error: ${error.message}` }] };

packages/@n8n/nodes-langchain/nodes/mcp/McpTrigger/McpTrigger.node.ts

@@ -17,8 +17,8 @@ export class McpTrigger extends Node {
 		displayName: 'MCP Server Trigger',
 		name: 'mcpTrigger',
 		icon: {
-			light: 'file:mcp.svg',
+			light: 'file:../mcp.svg',
-			dark: 'file:mcp.dark.svg',
+			dark: 'file:../mcp.dark.svg',
 		},
 		group: ['trigger'],
 		version: 1,
@@ -27,6 +27,21 @@ export class McpTrigger extends Node {
 		defaults: {
 			name: 'MCP Server Trigger',
 		},
+		codex: {
+			categories: ['AI', 'Core Nodes'],
+			subcategories: {
+				AI: ['Root Nodes', 'Model Context Protocol'],
+				'Core Nodes': ['Other Trigger Nodes'],
+			},
+			alias: ['Model Context Protocol', 'MCP Server'],
+			resources: {
+				primaryDocumentation: [
+					{
+						url: 'https://docs.n8n.io/integrations/builtin/core-nodes/n8n-nodes-langchain.mcptrigger/',
+					},
+				],
+			},
+		},
 		triggerPanel: {
 			header: 'Listen for MCP events',
 			executionsHelp: {
@@ -65,15 +80,6 @@ export class McpTrigger extends Node {
 					},
 				},
 			},
-			{
-				name: 'httpCustomAuth',
-				required: true,
-				displayOptions: {
-					show: {
-						authentication: ['customAuth'],
-					},
-				},
-			},
 		],
 		properties: [
 			{
@@ -84,7 +90,6 @@ export class McpTrigger extends Node {
 					{ name: 'None', value: 'none' },
 					{ name: 'Bearer Auth', value: 'bearerAuth' },
 					{ name: 'Header Auth', value: 'headerAuth' },
-					{ name: 'Custom Auth', value: 'customAuth' },
 				],
 				default: 'none',
 				description: 'The way to authenticate',

packages/@n8n/nodes-langchain/package.json

@@ -83,7 +83,8 @@
       "dist/nodes/llms/LMCohere/LmCohere.node.js",
       "dist/nodes/llms/LMOllama/LmOllama.node.js",
       "dist/nodes/llms/LMOpenHuggingFaceInference/LmOpenHuggingFaceInference.node.js",
-      "dist/nodes/Mcp/McpTrigger.node.js",
+      "dist/nodes/mcp/McpClientTool/McpClientTool.node.js",
+      "dist/nodes/mcp/McpTrigger/McpTrigger.node.js",
       "dist/nodes/memory/MemoryBufferWindow/MemoryBufferWindow.node.js",
       "dist/nodes/memory/MemoryMotorhead/MemoryMotorhead.node.js",
       "dist/nodes/memory/MemoryPostgresChat/MemoryPostgresChat.node.js",

packages/@n8n/nodes-langchain/utils/helpers.ts

@@ -3,6 +3,7 @@ import type { BaseChatModel } from '@langchain/core/language_models/chat_models'
 import type { BaseLLM } from '@langchain/core/language_models/llms';
 import type { BaseMessage } from '@langchain/core/messages';
 import type { Tool } from '@langchain/core/tools';
+import { Toolkit } from 'langchain/agents';
 import type { BaseChatMemory } from 'langchain/memory';
 import { NodeConnectionTypes, NodeOperationError, jsonStringify } from 'n8n-workflow';
 import type {
@@ -189,14 +190,22 @@ export const getConnectedTools = async (
 	convertStructuredTool: boolean = true,
 	escapeCurlyBrackets: boolean = false,
 ) => {
-	const connectedTools =
+	const connectedTools = (
-		((await ctx.getInputConnectionData(NodeConnectionTypes.AiTool, 0)) as Tool[]) || [];
+		((await ctx.getInputConnectionData(NodeConnectionTypes.AiTool, 0)) as Array<Toolkit | Tool>) ??
+		[]
+	).flatMap((toolOrToolkit) => {
+		if (toolOrToolkit instanceof Toolkit) {
+			return toolOrToolkit.getTools() as Tool[];
+		}
+
+		return toolOrToolkit;
+	});
 
 	if (!enforceUniqueNames) return connectedTools;
 
 	const seenNames = new Set<string>();
 
-	const finalTools = [];
+	const finalTools: Tool[] = [];
 
 	for (const tool of connectedTools) {
 		const { name } = tool;

packages/@n8n/nodes-langchain/utils/logWrapper.ts

@@ -6,11 +6,12 @@ import { Embeddings } from '@langchain/core/embeddings';
 import type { InputValues, MemoryVariables, OutputValues } from '@langchain/core/memory';
 import type { BaseMessage } from '@langchain/core/messages';
 import { BaseRetriever } from '@langchain/core/retrievers';
-import type { Tool } from '@langchain/core/tools';
+import type { StructuredTool, Tool } from '@langchain/core/tools';
 import { VectorStore } from '@langchain/core/vectorstores';
 import { TextSplitter } from '@langchain/textsplitters';
 import type { BaseDocumentLoader } from 'langchain/dist/document_loaders/base';
 import type {
+	IDataObject,
 	IExecuteFunctions,
 	INodeExecutionData,
 	ISupplyDataFunctions,
@@ -94,9 +95,10 @@ export function callMethodSync<T>(
 	}
 }
 
-export function logWrapper(
+export function logWrapper<
-	originalInstance:
+	T extends
 		| Tool
+		| StructuredTool
 		| BaseChatMemory
 		| BaseChatMessageHistory
 		| BaseRetriever
@@ -108,8 +110,7 @@ export function logWrapper(
 		| VectorStore
 		| N8nBinaryLoader
 		| N8nJsonLoader,
-	executeFunctions: IExecuteFunctions | ISupplyDataFunctions,
+>(originalInstance: T, executeFunctions: IExecuteFunctions | ISupplyDataFunctions): T {
-) {
 	return new Proxy(originalInstance, {
 		get: (target, prop) => {
 			let connectionType: NodeConnectionType | undefined;
@@ -372,8 +373,16 @@ export function logWrapper(
 				if (prop === '_call' && '_call' in target) {
 					return async (query: string): Promise<string> => {
 						connectionType = NodeConnectionTypes.AiTool;
+						const inputData: IDataObject = { query };
+
+						if (target.metadata?.isFromToolkit) {
+							inputData.tool = {
+								name: target.name,
+								description: target.description,
+							};
+						}
 						const { index } = executeFunctions.addInputData(connectionType, [
-							[{ json: { query } }],
+							[{ json: inputData }],
 						]);
 
 						const response = (await callMethodAsync.call(target, {
@@ -384,7 +393,7 @@ export function logWrapper(
 							arguments: [query],
 						})) as string;
 
-						logAiEvent(executeFunctions, 'ai-tool-called', { query, response });
+						logAiEvent(executeFunctions, 'ai-tool-called', { ...inputData, response });
 						executeFunctions.addOutputData(connectionType, index, [[{ json: { response } }]]);
 						return response;
 					};

packages/@n8n/nodes-langchain/utils/tests/helpers.test.ts

@@ -1,4 +1,5 @@
 import { DynamicTool, type Tool } from '@langchain/core/tools';
+import { Toolkit } from 'langchain/agents';
 import { createMockExecuteFunction } from 'n8n-nodes-base/test/nodes/Helpers';
 import { NodeOperationError } from 'n8n-workflow';
 import type { ISupplyDataFunctions, IExecuteFunctions, INode } from 'n8n-workflow';
@@ -242,6 +243,34 @@ describe('getConnectedTools', () => {
 		const tools = await getConnectedTools(mockExecuteFunctions, true, false);
 		expect(tools[0]).toBe(mockN8nTool);
 	});
+
+	it('should flatten tools from a toolkit', async () => {
+		class MockToolkit extends Toolkit {
+			tools: Tool[];
+
+			constructor(tools: unknown[]) {
+				super();
+				this.tools = tools as Tool[];
+			}
+		}
+		const mockTools = [
+			{ name: 'tool1', description: 'desc1' },
+
+			new MockToolkit([
+				{ name: 'toolkitTool1', description: 'toolkitToolDesc1' },
+				{ name: 'toolkitTool2', description: 'toolkitToolDesc2' },
+			]),
+		];
+
+		mockExecuteFunctions.getInputConnectionData = jest.fn().mockResolvedValue(mockTools);
+
+		const tools = await getConnectedTools(mockExecuteFunctions, false);
+		expect(tools).toEqual([
+			{ name: 'tool1', description: 'desc1' },
+			{ name: 'toolkitTool1', description: 'toolkitToolDesc1' },
+			{ name: 'toolkitTool2', description: 'toolkitToolDesc2' },
+		]);
+	});
 });
 
 describe('unwrapNestedOutput', () => {

packages/cli/src/load-nodes-and-credentials.ts

@@ -400,6 +400,13 @@ export class LoadNodesAndCredentials {
 		}
 	}
 
+	recognizesNode(fullNodeType: string): boolean {
+		const [packageName, nodeType] = fullNodeType.split('.');
+		const { loaders } = this;
+		const loader = loaders[packageName];
+		return !!loader && nodeType in loader.known.nodes;
+	}
+
 	getNode(fullNodeType: string): LoadedClass<INodeType | IVersionedNodeType> {
 		const [packageName, nodeType] = fullNodeType.split('.');
 		const { loaders } = this;

packages/cli/src/node-types.ts

@@ -37,6 +37,12 @@ export class NodeTypes implements INodeTypes {
 
 		const toolRequested = nodeType.endsWith('Tool');
 
+		// If an existing node name ends in `Tool`, then return that node, instead of creating a fake Tool node
+		if (toolRequested && this.loadNodesAndCredentials.recognizesNode(nodeType)) {
+			const node = this.loadNodesAndCredentials.getNode(nodeType);
+			return NodeHelpers.getVersionedNodeType(node.type, version);
+		}
+
 		// Make sure the nodeType to actually get from disk is the un-wrapped type
 		if (toolRequested) {
 			nodeType = nodeType.replace(/Tool$/, '');

packages/frontend/editor-ui/src/components/Node/NodeCreator/composables/useViewStacks.ts

@@ -6,6 +6,7 @@ import type {
 	SimplifiedNodeType,
 } from '@/Interface';
 import {
+	AI_CATEGORY_MCP_NODES,
 	AI_CATEGORY_ROOT_NODES,
 	AI_CATEGORY_TOOLS,
 	AI_CODE_NODE_TYPE,
@@ -222,15 +223,16 @@ export const useViewStacks = defineStore('nodeCreatorViewStacks', () => {
 			const aiSubNodes = difference(aiNodes, aiRootNodes);
 
 			aiSubNodes.forEach((node) => {
-				const section = node.properties.codex?.subcategories?.[AI_SUBCATEGORY]?.[0];
+				const subcategories = node.properties.codex?.subcategories ?? {};
+				const section = subcategories[AI_SUBCATEGORY]?.[0];
 
 				if (section) {
-					const subSection = node.properties.codex?.subcategories?.[section]?.[0];
+					const subSection = subcategories[section]?.[0];
 					const sectionKey = subSection ?? section;
 					const currentItems = sectionsMap.get(sectionKey)?.items ?? [];
-					const isSubnodesSection =
+					const isSubnodesSection = !(
-						!node.properties.codex?.subcategories?.[AI_SUBCATEGORY].includes(
+						subcategories[AI_SUBCATEGORY].includes(AI_CATEGORY_ROOT_NODES) ||
-							AI_CATEGORY_ROOT_NODES,
+						subcategories[AI_SUBCATEGORY].includes(AI_CATEGORY_MCP_NODES)
 					);
 
 					let title = section;

packages/frontend/editor-ui/src/components/Node/NodeCreator/utils.ts

@@ -57,12 +57,18 @@ export function subcategorizeItems(items: SimplifiedNodeType[]) {
 		// Only some subcategories are allowed
 		let subcategories: string[] = [DEFAULT_SUBCATEGORY];
 
-		WHITE_LISTED_SUBCATEGORIES.forEach((category) => {
+		const matchedSubcategories = WHITE_LISTED_SUBCATEGORIES.flatMap((category) => {
 			if (item.codex?.categories?.includes(category)) {
-				subcategories = item.codex?.subcategories?.[category] ?? [];
+				return item.codex?.subcategories?.[category] ?? [];
 			}
+
+			return [];
 		});
 
+		if (matchedSubcategories.length > 0) {
+			subcategories = matchedSubcategories;
+		}
+
 		subcategories.forEach((subcategory: string) => {
 			if (!acc[subcategory]) {
 				acc[subcategory] = [];

packages/frontend/editor-ui/src/constants.ts

@@ -118,6 +118,7 @@ export const BAMBOO_HR_NODE_TYPE = 'n8n-nodes-base.bambooHr';
 export const CALENDLY_TRIGGER_NODE_TYPE = 'n8n-nodes-base.calendlyTrigger';
 export const CODE_NODE_TYPE = 'n8n-nodes-base.code';
 export const AI_CODE_NODE_TYPE = '@n8n/n8n-nodes-langchain.code';
+export const AI_MCP_TOOL_NODE_TYPE = '@n8n/n8n-nodes-langchain.mcpClientTool';
 export const CRON_NODE_TYPE = 'n8n-nodes-base.cron';
 export const CLEARBIT_NODE_TYPE = 'n8n-nodes-base.clearbit';
 export const FILTER_NODE_TYPE = 'n8n-nodes-base.filter';
@@ -298,6 +299,7 @@ export const AI_CATEGORY_DOCUMENT_LOADERS = 'Document Loaders';
 export const AI_CATEGORY_TEXT_SPLITTERS = 'Text Splitters';
 export const AI_CATEGORY_OTHER_TOOLS = 'Other Tools';
 export const AI_CATEGORY_ROOT_NODES = 'Root Nodes';
+export const AI_CATEGORY_MCP_NODES = 'Model Context Protocol';
 export const AI_UNCATEGORIZED_CATEGORY = 'Miscellaneous';
 export const AI_CODE_TOOL_LANGCHAIN_NODE_TYPE = '@n8n/n8n-nodes-langchain.toolCode';
 export const AI_WORKFLOW_TOOL_LANGCHAIN_NODE_TYPE = '@n8n/n8n-nodes-langchain.toolWorkflow';

packages/frontend/editor-ui/src/utils/fromAIOverrideUtils.ts

@@ -46,7 +46,12 @@ function sanitizeFromAiParameterName(s: string) {
 }
 
 // nodeName | [nodeName, highestUnsupportedVersion]
-const NODE_DENYLIST = ['toolCode', 'toolHttpRequest', ['toolWorkflow', 1.2]] as const;
+const NODE_DENYLIST = [
+	'toolCode',
+	'toolHttpRequest',
+	'mcpClientTool',
+	['toolWorkflow', 1.2],
+] as const;
 
 const PATH_DENYLIST = [
 	'parameters.name',

packages/frontend/editor-ui/src/utils/nodeViewUtils.ts

@@ -1,4 +1,5 @@
 import {
+	AI_MCP_TOOL_NODE_TYPE,
 	LIST_LIKE_NODE_OPERATIONS,
 	MAIN_HEADER_TABS,
 	NODE_POSITION_CONFLICT_ALLOWLIST,
@@ -281,7 +282,11 @@ export function getGenericHints({
 	const nodeHints: NodeHint[] = [];
 
 	// tools hints
-	if (node?.type.toLocaleLowerCase().includes('tool') && hasNodeRun) {
+	if (
+		node?.type.toLocaleLowerCase().includes('tool') &&
+		node?.type !== AI_MCP_TOOL_NODE_TYPE &&
+		hasNodeRun
+	) {
 		const stringifiedParameters = JSON.stringify(workflowNode.parameters);
 		if (!stringifiedParameters.includes('$fromAI')) {
 			nodeHints.push({