fix(AI Agent Node): Escape curly brackets in tools description for non Tool agents (#11772)

packages/@n8n/nodes-langchain/nodes/agents/Agent/agents/ConversationalAgent/execute.ts

@@ -31,7 +31,7 @@ export async function conversationalAgentExecute(
 		| BaseChatMemory
 		| undefined;
 
-	const tools = await getConnectedTools(this, nodeVersion >= 1.5);
+	const tools = await getConnectedTools(this, nodeVersion >= 1.5, true, true);
 	const outputParsers = await getOptionalOutputParsers(this);
 
 	await checkForStructuredTools(tools, this.getNode(), 'Conversational Agent');

packages/@n8n/nodes-langchain/nodes/agents/Agent/agents/PlanAndExecuteAgent/execute.ts

@@ -26,7 +26,7 @@ export async function planAndExecuteAgentExecute(
 		0,
 	)) as BaseChatModel;
 
-	const tools = await getConnectedTools(this, nodeVersion >= 1.5);
+	const tools = await getConnectedTools(this, nodeVersion >= 1.5, true, true);
 
 	await checkForStructuredTools(tools, this.getNode(), 'Plan & Execute Agent');
 	const outputParsers = await getOptionalOutputParsers(this);

packages/@n8n/nodes-langchain/nodes/agents/Agent/agents/ReActAgent/execute.ts

@@ -31,7 +31,7 @@ export async function reActAgentAgentExecute(
 		| BaseLanguageModel
 		| BaseChatModel;
 
-	const tools = await getConnectedTools(this, nodeVersion >= 1.5);
+	const tools = await getConnectedTools(this, nodeVersion >= 1.5, true, true);
 
 	await checkForStructuredTools(tools, this.getNode(), 'ReAct Agent');
 

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

@@ -165,10 +165,29 @@ export function serializeChatHistory(chatHistory: BaseMessage[]): string {
 		.join('\n');
 }
 
+export function escapeSingleCurlyBrackets(text?: string): string | undefined {
+	if (text === undefined) return undefined;
+
+	let result = text;
+
+	result = result
+		// First handle triple brackets to avoid interference with double brackets
+		.replace(/(?<!{){{{(?!{)/g, '{{{{')
+		.replace(/(?<!})}}}(?!})/g, '}}}}')
+		// Then handle single brackets, but only if they're not part of double brackets
+		// Convert single { to {{ if it's not already part of {{ or {{{
+		.replace(/(?<!{){(?!{)/g, '{{')
+		// Convert single } to }} if it's not already part of }} or }}}
+		.replace(/(?<!})}(?!})/g, '}}');
+
+	return result;
+}
+
 export const getConnectedTools = async (
 	ctx: IExecuteFunctions,
 	enforceUniqueNames: boolean,
 	convertStructuredTool: boolean = true,
+	escapeCurlyBrackets: boolean = false,
 ) => {
 	const connectedTools =
 		((await ctx.getInputConnectionData(NodeConnectionType.AiTool, 0)) as Tool[]) || [];
@@ -189,6 +208,10 @@ export const getConnectedTools = async (
 		}
 		seenNames.add(name);
 
+		if (escapeCurlyBrackets) {
+			tool.description = escapeSingleCurlyBrackets(tool.description) ?? tool.description;
+		}
+
 		if (convertStructuredTool && tool instanceof N8nTool) {
 			finalTools.push(tool.asDynamicTool());
 		} else {

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

@@ -0,0 +1,245 @@
+import { DynamicTool, type Tool } from '@langchain/core/tools';
+import { createMockExecuteFunction } from 'n8n-nodes-base/test/nodes/Helpers';
+import { NodeOperationError } from 'n8n-workflow';
+import type { IExecuteFunctions, INode } from 'n8n-workflow';
+import { z } from 'zod';
+
+import { escapeSingleCurlyBrackets, getConnectedTools } from '../helpers';
+import { N8nTool } from '../N8nTool';
+
+describe('escapeSingleCurlyBrackets', () => {
+	it('should return undefined when input is undefined', () => {
+		expect(escapeSingleCurlyBrackets(undefined)).toBeUndefined();
+	});
+
+	it('should escape single curly brackets', () => {
+		expect(escapeSingleCurlyBrackets('Hello {world}')).toBe('Hello {{world}}');
+		expect(escapeSingleCurlyBrackets('Test {value} here')).toBe('Test {{value}} here');
+	});
+
+	it('should not escape already double curly brackets', () => {
+		expect(escapeSingleCurlyBrackets('Hello {{world}}')).toBe('Hello {{world}}');
+		expect(escapeSingleCurlyBrackets('Test {{value}} here')).toBe('Test {{value}} here');
+	});
+
+	it('should handle mixed single and double curly brackets', () => {
+		expect(escapeSingleCurlyBrackets('Hello {{world}} and {earth}')).toBe(
+			'Hello {{world}} and {{earth}}',
+		);
+	});
+
+	it('should handle empty string', () => {
+		expect(escapeSingleCurlyBrackets('')).toBe('');
+	});
+	it('should handle string with no curly brackets', () => {
+		expect(escapeSingleCurlyBrackets('Hello world')).toBe('Hello world');
+	});
+
+	it('should handle string with only opening curly bracket', () => {
+		expect(escapeSingleCurlyBrackets('Hello { world')).toBe('Hello {{ world');
+	});
+
+	it('should handle string with only closing curly bracket', () => {
+		expect(escapeSingleCurlyBrackets('Hello world }')).toBe('Hello world }}');
+	});
+
+	it('should handle string with multiple single curly brackets', () => {
+		expect(escapeSingleCurlyBrackets('{Hello} {world}')).toBe('{{Hello}} {{world}}');
+	});
+
+	it('should handle string with alternating single and double curly brackets', () => {
+		expect(escapeSingleCurlyBrackets('{a} {{b}} {c} {{d}}')).toBe('{{a}} {{b}} {{c}} {{d}}');
+	});
+
+	it('should handle string with curly brackets at the start and end', () => {
+		expect(escapeSingleCurlyBrackets('{start} middle {end}')).toBe('{{start}} middle {{end}}');
+	});
+
+	it('should handle string with special characters', () => {
+		expect(escapeSingleCurlyBrackets('Special {!@#$%^&*} chars')).toBe(
+			'Special {{!@#$%^&*}} chars',
+		);
+	});
+
+	it('should handle string with numbers in curly brackets', () => {
+		expect(escapeSingleCurlyBrackets('Numbers {123} here')).toBe('Numbers {{123}} here');
+	});
+
+	it('should handle string with whitespace in curly brackets', () => {
+		expect(escapeSingleCurlyBrackets('Whitespace {  } here')).toBe('Whitespace {{  }} here');
+	});
+	it('should handle multi-line input with single curly brackets', () => {
+		const input = `
+      Line 1 {test}
+      Line 2 {another test}
+      Line 3
+    `;
+		const expected = `
+      Line 1 {{test}}
+      Line 2 {{another test}}
+      Line 3
+    `;
+		expect(escapeSingleCurlyBrackets(input)).toBe(expected);
+	});
+
+	it('should handle multi-line input with mixed single and double curly brackets', () => {
+		const input = `
+      {Line 1}
+      {{Line 2}}
+      Line {3} {{4}}
+    `;
+		const expected = `
+      {{Line 1}}
+      {{Line 2}}
+      Line {{3}} {{4}}
+    `;
+		expect(escapeSingleCurlyBrackets(input)).toBe(expected);
+	});
+
+	it('should handle multi-line input with curly brackets at line starts and ends', () => {
+		const input = `
+      {Start of line 1
+      End of line 2}
+      {3} Line 3 {3}
+    `;
+		const expected = `
+      {{Start of line 1
+      End of line 2}}
+      {{3}} Line 3 {{3}}
+    `;
+		expect(escapeSingleCurlyBrackets(input)).toBe(expected);
+	});
+
+	it('should handle multi-line input with nested curly brackets', () => {
+		const input = `
+      Outer {
+        Inner {nested}
+      }
+    `;
+		const expected = `
+      Outer {{
+        Inner {{nested}}
+      }}
+    `;
+		expect(escapeSingleCurlyBrackets(input)).toBe(expected);
+	});
+	it('should handle string with triple uneven curly brackets - opening', () => {
+		expect(escapeSingleCurlyBrackets('Hello {{{world}')).toBe('Hello {{{{world}}');
+	});
+
+	it('should handle string with triple uneven curly brackets - closing', () => {
+		expect(escapeSingleCurlyBrackets('Hello world}}}')).toBe('Hello world}}}}');
+	});
+
+	it('should handle string with triple uneven curly brackets - mixed opening and closing', () => {
+		expect(escapeSingleCurlyBrackets('{{{Hello}}} {world}}}')).toBe('{{{{Hello}}}} {{world}}}}');
+	});
+
+	it('should handle string with triple uneven curly brackets - multiple occurrences', () => {
+		expect(escapeSingleCurlyBrackets('{{{a}}} {{b}}} {{{c}')).toBe('{{{{a}}}} {{b}}}} {{{{c}}');
+	});
+
+	it('should handle multi-line input with triple uneven curly brackets', () => {
+		const input = `
+					{{{Line 1}
+					Line 2}}}
+					{{{3}}} Line 3 {{{4
+			`;
+		const expected = `
+					{{{{Line 1}}
+					Line 2}}}}
+					{{{{3}}}} Line 3 {{{{4
+			`;
+		expect(escapeSingleCurlyBrackets(input)).toBe(expected);
+	});
+});
+
+describe('getConnectedTools', () => {
+	let mockExecuteFunctions: IExecuteFunctions;
+	let mockNode: INode;
+	let mockN8nTool: N8nTool;
+
+	beforeEach(() => {
+		mockNode = {
+			id: 'test-node',
+			name: 'Test Node',
+			type: 'test',
+			typeVersion: 1,
+			position: [0, 0],
+			parameters: {},
+		};
+
+		mockExecuteFunctions = createMockExecuteFunction({}, mockNode);
+
+		mockN8nTool = new N8nTool(mockExecuteFunctions, {
+			name: 'Dummy Tool',
+			description: 'A dummy tool for testing',
+			func: jest.fn(),
+			schema: z.object({
+				foo: z.string(),
+			}),
+		});
+	});
+
+	it('should return empty array when no tools are connected', async () => {
+		mockExecuteFunctions.getInputConnectionData = jest.fn().mockResolvedValue([]);
+
+		const tools = await getConnectedTools(mockExecuteFunctions, true);
+		expect(tools).toEqual([]);
+	});
+
+	it('should return tools without modification when enforceUniqueNames is false', async () => {
+		const mockTools = [
+			{ name: 'tool1', description: 'desc1' },
+			{ name: 'tool1', description: 'desc2' }, // Duplicate name
+		];
+
+		mockExecuteFunctions.getInputConnectionData = jest.fn().mockResolvedValue(mockTools);
+
+		const tools = await getConnectedTools(mockExecuteFunctions, false);
+		expect(tools).toEqual(mockTools);
+	});
+
+	it('should throw error when duplicate tool names exist and enforceUniqueNames is true', async () => {
+		const mockTools = [
+			{ name: 'tool1', description: 'desc1' },
+			{ name: 'tool1', description: 'desc2' },
+		];
+
+		mockExecuteFunctions.getInputConnectionData = jest.fn().mockResolvedValue(mockTools);
+
+		await expect(getConnectedTools(mockExecuteFunctions, true)).rejects.toThrow(NodeOperationError);
+	});
+
+	it('should escape curly brackets in tool descriptions when escapeCurlyBrackets is true', async () => {
+		const mockTools = [{ name: 'tool1', description: 'Test {value}' }] as Tool[];
+
+		mockExecuteFunctions.getInputConnectionData = jest.fn().mockResolvedValue(mockTools);
+
+		const tools = await getConnectedTools(mockExecuteFunctions, true, false, true);
+		expect(tools[0].description).toBe('Test {{value}}');
+	});
+
+	it('should convert N8nTool to dynamic tool when convertStructuredTool is true', async () => {
+		const mockDynamicTool = new DynamicTool({
+			name: 'dynamicTool',
+			description: 'desc',
+			func: jest.fn(),
+		});
+		const asDynamicToolSpy = jest.fn().mockReturnValue(mockDynamicTool);
+		mockN8nTool.asDynamicTool = asDynamicToolSpy;
+
+		mockExecuteFunctions.getInputConnectionData = jest.fn().mockResolvedValue([mockN8nTool]);
+
+		const tools = await getConnectedTools(mockExecuteFunctions, true, true);
+		expect(asDynamicToolSpy).toHaveBeenCalled();
+		expect(tools[0]).toEqual(mockDynamicTool);
+	});
+
+	it('should not convert N8nTool when convertStructuredTool is false', async () => {
+		mockExecuteFunctions.getInputConnectionData = jest.fn().mockResolvedValue([mockN8nTool]);
+
+		const tools = await getConnectedTools(mockExecuteFunctions, true, false);
+		expect(tools[0]).toBe(mockN8nTool);
+	});
+});