feat(core): Implement wrapping of regular nodes as AI Tools

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

@@ -1,10 +1,10 @@
+import { NodeConnectionType, NodeOperationError, jsonStringify } from 'n8n-workflow';
 import type {
 	EventNamesAiNodesType,
 	IDataObject,
 	IExecuteFunctions,
 	IWebhookFunctions,
 } from 'n8n-workflow';
-import { NodeConnectionType, NodeOperationError, jsonStringify } from 'n8n-workflow';
 import type { BaseChatModel } from '@langchain/core/language_models/chat_models';
 import type { BaseOutputParser } from '@langchain/core/output_parsers';
 import type { BaseMessage } from '@langchain/core/messages';

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

@@ -13,11 +13,12 @@ import {
 } from 'n8n-core';
 import type {
 	KnownNodesAndCredentials,
+	INodeTypeBaseDescription,
 	INodeTypeDescription,
 	INodeTypeData,
 	ICredentialTypeData,
 } from 'n8n-workflow';
-import { ApplicationError, ErrorReporterProxy as ErrorReporter } from 'n8n-workflow';
+import { NodeHelpers, ApplicationError, ErrorReporterProxy as ErrorReporter } from 'n8n-workflow';
 
 import {
 	CUSTOM_API_CALL_KEY,
@@ -38,8 +39,11 @@ interface LoadedNodesAndCredentials {
 export class LoadNodesAndCredentials {
 	private known: KnownNodesAndCredentials = { nodes: {}, credentials: {} };
 
+	// This contains the actually loaded objects, and their source paths
 	loaded: LoadedNodesAndCredentials = { nodes: {}, credentials: {} };
 
+	// For nodes, this only contains the descriptions, loaded from either the
+	// actual file, or the lazy loaded json
 	types: Types = { nodes: [], credentials: [] };
 
 	loaders: Record<string, DirectoryLoader> = {};
@@ -260,6 +264,34 @@ export class LoadNodesAndCredentials {
 		return loader;
 	}
 
+	/**
+	 * This creates all AI Agent tools by duplicating the node descriptions for
+	 * all nodes that are marked as `usableAsTool`. It basically modifies the
+	 * description. The actual wrapping happens in the langchain code for getting
+	 * the connected tools.
+	 */
+	createAiTools() {
+		const usableNodes: Array<INodeTypeBaseDescription | INodeTypeDescription> =
+			this.types.nodes.filter((nodetype) => nodetype.usableAsTool === true);
+
+		for (const usableNode of usableNodes) {
+			const description: INodeTypeBaseDescription | INodeTypeDescription =
+				structuredClone(usableNode);
+			const wrapped = NodeHelpers.convertNodeToAiTool({ description }).description;
+
+			this.types.nodes.push(wrapped);
+			this.known.nodes[wrapped.name] = structuredClone(this.known.nodes[usableNode.name]);
+
+			const credentialNames = Object.entries(this.known.credentials)
+				.filter(([_, credential]) => credential?.supportedNodes?.includes(usableNode.name))
+				.map(([credentialName]) => credentialName);
+
+			credentialNames.forEach((name) =>
+				this.known.credentials[name]?.supportedNodes?.push(wrapped.name),
+			);
+		}
+	}
+
 	async postProcessLoaders() {
 		this.known = { nodes: {}, credentials: {} };
 		this.loaded = { nodes: {}, credentials: {} };
@@ -307,6 +339,8 @@ export class LoadNodesAndCredentials {
 			}
 		}
 
+		this.createAiTools();
+
 		this.injectCustomApiCallOptions();
 
 		for (const postProcessor of this.postProcessors) {

packages/cli/src/node-types.ts

@@ -43,7 +43,15 @@ export class NodeTypes implements INodeTypes {
 	}
 
 	getByNameAndVersion(nodeType: string, version?: number): INodeType {
-		return NodeHelpers.getVersionedNodeType(this.getNode(nodeType).type, version);
+		const versionedNodeType = NodeHelpers.getVersionedNodeType(
+			this.getNode(nodeType).type,
+			version,
+		);
+		if (versionedNodeType.description.usableAsTool) {
+			return NodeHelpers.convertNodeToAiTool(versionedNodeType);
+		}
+
+		return versionedNodeType;
 	}
 
 	/* Some nodeTypes need to get special parameters applied like the polling nodes the polling times */
@@ -66,8 +74,9 @@ export class NodeTypes implements INodeTypes {
 
 		if (type in knownNodes) {
 			const { className, sourcePath } = knownNodes[type];
-			const loaded: INodeType = loadClassInIsolation(sourcePath, className);
-			NodeHelpers.applySpecialNodeParameters(loaded);
+			const loaded: INodeType | IVersionedNodeType = loadClassInIsolation(sourcePath, className);
+			if (NodeHelpers.isINodeType(loaded)) NodeHelpers.applySpecialNodeParameters(loaded);
+
 			loadedNodes[type] = { sourcePath, type: loaded };
 			return loadedNodes[type];
 		}

packages/core/package.json

@@ -44,6 +44,7 @@
     "file-type": "16.5.4",
     "form-data": "catalog:",
     "lodash": "catalog:",
+    "@langchain/core": "0.2.18",
     "luxon": "catalog:",
     "mime-types": "2.1.35",
     "n8n-workflow": "workspace:*",
@@ -54,6 +55,7 @@
     "ssh2": "1.15.0",
     "typedi": "catalog:",
     "uuid": "catalog:",
-    "xml2js": "catalog:"
+    "xml2js": "catalog:",
+    "zod": "catalog:"
   }
 }