feat: add n8n_generate_workflow tool for hosted workflow generation

Add new MCP tool that enables AI-powered workflow generation from natural
language descriptions. Uses handler delegation pattern — hosting environments
inject a GenerateWorkflowHandler via EngineOptions, self-hosted instances
receive a hosted-only informational response.

Handler flows through N8NMCPEngine → SingleSessionHTTPServer →
N8NDocumentationMCPServer with helpers for createWorkflow, validateWorkflow,
autofixWorkflow, and getWorkflow.

Includes full tool documentation, tests, and corrected tools overview count.

Conceived by Romuald Członkowski - https://www.aiadvisors.pl/en

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/mcp/tool-docs/index.ts

@@ -23,7 +23,8 @@ import {
   n8nExecutionsDoc,
   n8nWorkflowVersionsDoc,
   n8nDeployTemplateDoc,
-  n8nManageDatatableDoc
+  n8nManageDatatableDoc,
+  n8nGenerateWorkflowDoc
 } from './workflow_management';
 
 // Combine all tool documentations into a single object
@@ -62,7 +63,8 @@ export const toolsDocumentation: Record<string, ToolDocumentation> = {
   n8n_executions: n8nExecutionsDoc,
   n8n_workflow_versions: n8nWorkflowVersionsDoc,
   n8n_deploy_template: n8nDeployTemplateDoc,
-  n8n_manage_datatable: n8nManageDatatableDoc
+  n8n_manage_datatable: n8nManageDatatableDoc,
+  n8n_generate_workflow: n8nGenerateWorkflowDoc
 };
 
 // Re-export types

src/mcp/tool-docs/workflow_management/index.ts

@@ -11,3 +11,4 @@ export { n8nExecutionsDoc } from './n8n-executions';
 export { n8nWorkflowVersionsDoc } from './n8n-workflow-versions';
 export { n8nDeployTemplateDoc } from './n8n-deploy-template';
 export { n8nManageDatatableDoc } from './n8n-manage-datatable';
+export { n8nGenerateWorkflowDoc } from './n8n-generate-workflow';

src/mcp/tool-docs/workflow_management/n8n-generate-workflow.ts

@@ -0,0 +1,62 @@
+import { ToolDocumentation } from '../types';
+
+export const n8nGenerateWorkflowDoc: ToolDocumentation = {
+  name: 'n8n_generate_workflow',
+  category: 'workflow_management',
+  essentials: {
+    description: 'Generate an n8n workflow from a natural language description using AI. Creates and deploys a ready-to-use workflow to your n8n instance.',
+    keyParameters: ['description', 'skip_cache'],
+    example: 'n8n_generate_workflow({description: "Send a Slack message every morning at 9am"})',
+    performance: 'Network-dependent (2-15s depending on cache hit vs fresh generation)',
+    tips: [
+      'Include trigger type (webhook, schedule, manual) in the description',
+      'Mention specific services to integrate (Slack, Gmail, Google Sheets, etc.)',
+      'Use skip_cache=true to force fresh AI generation instead of cached templates',
+      'Available exclusively on the hosted version of n8n-mcp'
+    ]
+  },
+  full: {
+    description: 'Generates an n8n workflow from a natural language description using AI. On the hosted service, this tool first searches a cache of 73,000+ pre-built workflows for a match, and falls back to AI-powered fresh generation for custom workflows. Generated workflows are automatically validated and error-corrected before deployment. On self-hosted instances, this tool returns a message directing users to the hosted service.',
+    parameters: {
+      description: { type: 'string', required: true, description: 'Clear description of what the workflow should do. Include: trigger type (webhook, schedule, manual), services to integrate (Slack, Gmail, etc.), and the logic/flow.' },
+      skip_cache: { type: 'boolean', description: 'Set to true to bypass the workflow cache and force fresh AI generation. Default: false (uses cached workflows when a good match exists).' }
+    },
+    returns: 'Object with success, source (cache/generated), workflow_id, workflow_name, workflow_url, node_count, node_summary, and message. On self-hosted instances, returns hosted_only: true with information about the hosted service.',
+    examples: [
+      `// Generate a simple scheduled workflow
+n8n_generate_workflow({
+  description: "Send a Slack message every morning at 9am with a daily standup reminder"
+})`,
+      `// Generate with specific services
+n8n_generate_workflow({
+  description: "When a new row is added to Google Sheets, create a task in Notion and notify via email"
+})`,
+      `// Force fresh generation (skip cache)
+n8n_generate_workflow({
+  description: "Webhook that receives JSON data, transforms it, and posts to a REST API",
+  skip_cache: true
+})`
+    ],
+    useCases: [
+      'Quickly create workflows from natural language descriptions',
+      'Generate complex multi-service integrations',
+      'Bootstrap automation projects with AI-generated workflows',
+      'Create workflows without deep knowledge of n8n node configuration'
+    ],
+    performance: 'Cache hit: ~2s. Fresh generation: 5-15s. Both within typical MCP client timeout.',
+    bestPractices: [
+      'Be specific about trigger type and services in the description',
+      'Review generated workflows before activating',
+      'Use n8n_validate_workflow to check the generated workflow',
+      'Configure credentials in n8n UI before activating',
+      'Use skip_cache only when cached results do not match your needs'
+    ],
+    pitfalls: [
+      '**Hosted-only feature** — self-hosted instances receive a redirect message',
+      'Generated workflows are created in INACTIVE state',
+      'Credentials must be configured manually in the n8n UI',
+      'Complex workflows may need manual adjustments after generation'
+    ],
+    relatedTools: ['n8n_create_workflow', 'n8n_deploy_template', 'n8n_validate_workflow', 'n8n_autofix_workflow', 'search_templates']
+  }
+};