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

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 { McpServerTransport, 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, 1.1],
		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.toolmcp/',
					},
				],
			},
		},
		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,
				displayOptions: {
					show: {
						'@version': [1],
					},
				},
			},
			{
				displayName: 'Endpoint',
				name: 'endpointUrl',
				type: 'string',
				description: 'Endpoint of your MCP server',
				placeholder: 'e.g. https://my-mcp-server.ai/mcp',
				default: '',
				required: true,
				displayOptions: {
					show: {
						'@version': [{ _cnd: { gte: 1.1 } }],
					},
				},
			},
			{
				displayName: 'Server Transport',
				name: 'serverTransport',
				type: 'options',
				options: [
					{
						name: 'Server Sent Events (Deprecated)',
						value: 'sse',
					},
					{
						name: 'HTTP Streamable',
						value: 'httpStreamable',
					},
				],
				default: 'sse',
				description: 'The transport used by your endpoint',
				displayOptions: {
					show: {
						'@version': [{ _cnd: { gte: 1.1 } }],
					},
				},
			},
			{
				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 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 node = this.getNode();

		let serverTransport: McpServerTransport;
		let endpointUrl: string;
		if (node.typeVersion === 1) {
			serverTransport = 'sse';
			endpointUrl = this.getNodeParameter('sseEndpoint', itemIndex) as string;
		} else {
			serverTransport = this.getNodeParameter('serverTransport', itemIndex) as McpServerTransport;
			endpointUrl = this.getNodeParameter('endpointUrl', itemIndex) as string;
		}

		const { headers } = await getAuthHeaders(this, authentication);
		const client = await connectMcpClient({
			serverTransport,
			endpointUrl,
			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() };
	}
}