feat(mcp-client): Add httpCustomAuth support

Author: leameow

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

@@ -188,6 +188,57 @@ describe('McpClientTool', () => {
 			expect(tools[0].name).toBe('MyTool1');
 		});
 
+		it('should support custom 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: 'customAuth',
+							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', json: '{"headers":{"h1": "v1", "h2": "v2"}}' }),
+				}),
+				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: { h1: 'v1', h2: 'v2' } },
+			});
+
+			const customFetch = jest.mocked(SSEClientTransport).mock.calls[0][1]?.eventSourceInit?.fetch;
+			await customFetch?.(url);
+			expect(fetchSpy).toHaveBeenCalledWith(url, {
+				headers: { Accept: 'text/event-stream', h1: 'v1', h2: 'v2' },
+			});
+		});
+
 		it('should support header auth', async () => {
 			jest.spyOn(Client.prototype, 'connect').mockResolvedValue();
 			jest.spyOn(Client.prototype, 'listTools').mockResolvedValue({

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

@@ -71,6 +71,15 @@ export class McpClientTool implements INodeType {
 					},
 				},
 			},
+			{
+				name: 'httpCustomAuth',
+				required: true,
+				displayOptions: {
+					show: {
+						authentication: ['customAuth'],
+					},
+				},
+			},
 		],
 		properties: [
 			getConnectionHintNoticeField([NodeConnectionTypes.AiAgent]),
@@ -137,6 +146,10 @@ export class McpClientTool implements INodeType {
 						name: 'Header Auth',
 						value: 'headerAuth',
 					},
+					{
+						name: 'Custom Auth',
+						value: 'customAuth',
+					},
 					{
 						name: 'None',
 						value: 'none',
@@ -152,7 +165,7 @@ export class McpClientTool implements INodeType {
 				default: '',
 				displayOptions: {
 					show: {
-						authentication: ['headerAuth', 'bearerAuth'],
+						authentication: ['headerAuth', 'bearerAuth', 'customAuth'],
 					},
 				},
 			},

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

@@ -6,4 +6,4 @@ export type McpServerTransport = 'sse' | 'httpStreamable';
 
 export type McpToolIncludeMode = 'all' | 'selected' | 'except';
 
-export type McpAuthenticationOption = 'none' | 'headerAuth' | 'bearerAuth';
+export type McpAuthenticationOption = 'none' | 'headerAuth' | 'bearerAuth' | 'customAuth';

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

@@ -8,8 +8,10 @@ import { Toolkit } from 'langchain/agents';
 import {
 	createResultError,
 	createResultOk,
+	jsonParse,
 	type IDataObject,
 	type IExecuteFunctions,
+	type IRequestOptionsSimplified,
 	type Result,
 } from 'n8n-workflow';
 import { z } from 'zod';
@@ -232,6 +234,19 @@ export async function getAuthHeaders(
 
 			return { headers: { Authorization: `Bearer ${result.token}` } };
 		}
+		case 'customAuth': {
+			const result = await ctx
+				.getCredentials<{ token: string }>('httpCustomAuth')
+				.catch(() => null);
+
+			if (!result) return {};
+
+			const customAuth = jsonParse<IRequestOptionsSimplified>((result.json as string) || '{}', {
+				errorMessage: 'Invalid Custom Auth JSON',
+			});
+
+			return { headers: customAuth.headers };
+		}
 		case 'none':
 		default: {
 			return {};