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/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 =
-		((await ctx.getInputConnectionData(NodeConnectionTypes.AiTool, 0)) as Tool[]) || [];
+	const connectedTools = (
+		((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(
-	originalInstance:
+export function logWrapper<
+	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', () => {