From 53b1ad7e5b6a53cdbe28a53e4db3ad8ba75fcae2 Mon Sep 17 00:00:00 2001
From: Ricardo Espinoza <ricardo@n8n.io>
Date: Wed, 2 Sep 2026 11:50:46 +0000
Subject: [PATCH] fix(core): List the valid techniques when
 get_workflow_best_practices rejects input (#37580)

---
 .../get-workflow-best-practices.tool.test.ts  | 31 +++++++++++++++++++
 .../get-workflow-best-practices.tool.ts       |  6 ++--
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/packages/cli/src/modules/mcp/__tests__/get-workflow-best-practices.tool.test.ts b/packages/cli/src/modules/mcp/__tests__/get-workflow-best-practices.tool.test.ts
index c21452faa25..33fd5bca08b 100644
--- a/packages/cli/src/modules/mcp/__tests__/get-workflow-best-practices.tool.test.ts
+++ b/packages/cli/src/modules/mcp/__tests__/get-workflow-best-practices.tool.test.ts
@@ -48,6 +48,37 @@ describe('get-workflow-best-practices MCP tool', () => {
 		expect(tool.config.inputSchema?.technique).toBeDefined();
 	});
 
+	describe('technique input schema', () => {
+		const techniqueSchema = () => createTool().config.inputSchema!.technique;
+
+		test('accepts every technique key and the list sentinel', () => {
+			const schema = techniqueSchema();
+
+			for (const value of ['list', ...Object.values(WorkflowTechnique)]) {
+				expect(schema.safeParse(value).success).toBe(true);
+			}
+		});
+
+		test('names the accepted values when the technique is unknown', () => {
+			const result = techniqueSchema().safeParse('webhook');
+
+			expect(result.success).toBe(false);
+			const message = result.error?.issues[0]?.message ?? '';
+			expect(message).not.toBe('Invalid input');
+			expect(message).toContain('list');
+			expect(message).toContain(WorkflowTechnique.CHATBOT);
+			expect(message).toContain(WorkflowTechnique.WEB_APP);
+		});
+
+		test('lists the accepted values in the parameter description', () => {
+			const description = techniqueSchema().description ?? '';
+
+			for (const value of ['list', ...Object.values(WorkflowTechnique)]) {
+				expect(description).toContain(value);
+			}
+		});
+	});
+
 	test('returns the full technique catalog when technique="list"', async () => {
 		const tool = createTool();
 		const result = await tool.handler({ technique: 'list' }, {} as never);
diff --git a/packages/cli/src/modules/mcp/tools/workflow-builder/get-workflow-best-practices.tool.ts b/packages/cli/src/modules/mcp/tools/workflow-builder/get-workflow-best-practices.tool.ts
index 74e84e9c992..8d3dc06ad13 100644
--- a/packages/cli/src/modules/mcp/tools/workflow-builder/get-workflow-best-practices.tool.ts
+++ b/packages/cli/src/modules/mcp/tools/workflow-builder/get-workflow-best-practices.tool.ts
@@ -16,11 +16,13 @@ import type { ToolDefinition, UserCalledMCPToolEventPayload } from '../../mcp.ty
 
 const LIST_SENTINEL = 'list';
 
+const TECHNIQUE_CHOICES = [LIST_SENTINEL, ...Object.values(WorkflowTechnique)] as const;
+
 const inputSchema = {
 	technique: z
-		.union([z.nativeEnum(WorkflowTechnique), z.literal(LIST_SENTINEL)])
+		.enum(TECHNIQUE_CHOICES)
 		.describe(
-			`Workflow technique key (e.g. "chatbot", "scheduling", "triage") to fetch best-practices guidance for. Pass "${LIST_SENTINEL}" to discover all available techniques.`,
+			`Workflow technique key to fetch best-practices guidance for. Pass "${LIST_SENTINEL}" to discover all available techniques. One of: ${TECHNIQUE_CHOICES.join(', ')}.`,
 		),
 } satisfies z.ZodRawShape;