n8n-mcp/CLAUDE.md

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

n8n-mcp is a comprehensive documentation and knowledge server that provides AI assistants with complete access to n8n node information through the Model Context Protocol (MCP). It serves as a bridge between n8n's workflow automation platform and AI models, enabling them to understand and work with n8n nodes effectively.

Current Architecture:

src/
├── loaders/
│   └── node-loader.ts         # NPM package loader for both packages
├── parsers/
│   ├── node-parser.ts         # Enhanced parser with version support
│   └── property-extractor.ts  # Dedicated property/operation extraction
├── mappers/
│   └── docs-mapper.ts         # Documentation mapping with fixes
├── database/
│   ├── schema.sql             # SQLite schema
│   ├── node-repository.ts     # Data access layer
│   └── database-adapter.ts    # Universal database adapter (NEW in v2.3)
├── services/
│   ├── property-filter.ts     # Filters properties to essentials (NEW in v2.4)
│   ├── example-generator.ts   # Generates working examples (NEW in v2.4)
│   ├── task-templates.ts      # Pre-configured node settings (NEW in v2.4)
│   ├── config-validator.ts    # Configuration validation (NEW in v2.4)
│   ├── enhanced-config-validator.ts # Operation-aware validation (NEW in v2.4.2)
│   ├── node-specific-validators.ts  # Node-specific validation logic (NEW in v2.4.2)
│   ├── property-dependencies.ts # Dependency analysis (NEW in v2.4)
│   ├── type-structure-service.ts # Type structure validation (NEW in v2.22.21)
│   ├── expression-validator.ts # n8n expression syntax validation (NEW in v2.5.0)
│   └── workflow-validator.ts  # Complete workflow validation (NEW in v2.5.0)
├── types/
│   ├── type-structures.ts      # Type structure definitions (NEW in v2.22.21)
│   ├── instance-context.ts     # Multi-tenant instance configuration
│   └── session-state.ts        # Session persistence types (NEW in v2.24.1)
├── constants/
│   └── type-structures.ts      # 22 complete type structures (NEW in v2.22.21)
├── templates/
│   ├── template-fetcher.ts    # Fetches templates from n8n.io API (NEW in v2.4.1)
│   ├── template-repository.ts # Template database operations (NEW in v2.4.1)
│   └── template-service.ts    # Template business logic (NEW in v2.4.1)
├── scripts/
│   ├── rebuild.ts             # Database rebuild with validation
│   ├── validate.ts            # Node validation
│   ├── test-nodes.ts          # Critical node tests
│   ├── test-essentials.ts     # Test new essentials tools (NEW in v2.4)
│   ├── test-enhanced-validation.ts # Test enhanced validation (NEW in v2.4.2)
│   ├── test-structure-validation.ts # Test type structure validation (NEW in v2.22.21)
│   ├── test-workflow-validation.ts # Test workflow validation (NEW in v2.5.0)
│   ├── test-ai-workflow-validation.ts # Test AI workflow validation (NEW in v2.5.1)
│   ├── test-mcp-tools.ts      # Test MCP tool enhancements (NEW in v2.5.1)
│   ├── test-n8n-validate-workflow.ts # Test n8n_validate_workflow tool (NEW in v2.6.3)
│   ├── test-typeversion-validation.ts # Test typeVersion validation (NEW in v2.6.1)
│   ├── test-workflow-diff.ts  # Test workflow diff engine (NEW in v2.7.0)
│   ├── test-tools-documentation.ts # Test tools documentation (NEW in v2.7.3)
│   ├── fetch-templates.ts     # Fetch workflow templates from n8n.io (NEW in v2.4.1)
│   └── test-templates.ts      # Test template functionality (NEW in v2.4.1)
├── mcp/
│   ├── server.ts              # MCP server with enhanced tools
│   ├── tools.ts               # Tool definitions including new essentials
│   ├── tools-documentation.ts # Tool documentation system (NEW in v2.7.3)
│   └── index.ts               # Main entry point with mode selection
├── utils/
│   ├── console-manager.ts     # Console output isolation (NEW in v2.3.1)
│   └── logger.ts              # Logging utility with HTTP awareness
├── http-server-single-session.ts  # Single-session HTTP server (NEW in v2.3.1)
│                                   # Session persistence API (NEW in v2.24.1)
├── mcp-engine.ts              # Clean API for service integration (NEW in v2.3.1)
│                                # Session persistence wrappers (NEW in v2.24.1)
└── index.ts                   # Library exports

Common Development Commands

# Build and Setup
npm run build          # Build TypeScript (always run after changes)
npm run rebuild        # Rebuild node database from n8n packages
npm run validate       # Validate all node data in database

# Testing
npm test               # Run all tests
npm run test:unit      # Run unit tests only
npm run test:integration # Run integration tests
npm run test:coverage  # Run tests with coverage report
npm run test:watch     # Run tests in watch mode
npm run test:structure-validation # Test type structure validation (Phase 3)

# Run a single test file
npm test -- tests/unit/services/property-filter.test.ts

# Linting and Type Checking
npm run lint           # Check TypeScript types (alias for typecheck)
npm run typecheck      # Check TypeScript types

# Running the Server
npm start              # Start MCP server in stdio mode
npm run start:http     # Start MCP server in HTTP mode
npm run dev            # Build, rebuild database, and validate
npm run dev:http       # Run HTTP server with auto-reload

# Update n8n Dependencies
npm run update:n8n:check  # Check for n8n updates (dry run)
npm run update:n8n        # Update n8n packages to latest

# Database Management
npm run db:rebuild     # Rebuild database from scratch
npm run migrate:fts5   # Migrate to FTS5 search (if needed)

# Template Management
npm run fetch:templates  # Fetch latest workflow templates from n8n.io
npm run test:templates   # Test template functionality

High-Level Architecture

Core Components

1. MCP Server (mcp/server.ts)

   • Implements Model Context Protocol for AI assistants
   • Provides tools for searching, validating, and managing n8n nodes
   • Supports both stdio (Claude Desktop) and HTTP modes

2. Database Layer (database/)

   • SQLite database storing all n8n node information
   • Universal adapter pattern supporting both better-sqlite3 and sql.js
   • Full-text search capabilities with FTS5

3. Node Processing Pipeline

   • Loader (loaders/node-loader.ts): Loads nodes from n8n packages
   • Parser (parsers/node-parser.ts): Extracts node metadata and structure
   • Property Extractor (parsers/property-extractor.ts): Deep property analysis
   • Docs Mapper (mappers/docs-mapper.ts): Maps external documentation

4. Service Layer (services/)

   • Property Filter: Reduces node properties to AI-friendly essentials
   • Config Validator: Multi-profile validation system
   • Type Structure Service: Validates complex type structures (filter, resourceMapper, etc.)
   • Expression Validator: Validates n8n expression syntax
   • Workflow Validator: Complete workflow structure validation

5. Template System (templates/)

   • Fetches and stores workflow templates from n8n.io
   • Provides pre-built workflow examples
   • Supports template search and validation

Key Design Patterns

1. Repository Pattern: All database operations go through repository classes
2. Service Layer: Business logic separated from data access
3. Validation Profiles: Different validation strictness levels (minimal, runtime, ai-friendly, strict)
4. Diff-Based Updates: Efficient workflow updates using operation diffs

MCP Tools Architecture

The MCP server exposes tools in several categories:

1. Discovery Tools: Finding and exploring nodes
2. Configuration Tools: Getting node details and examples
3. Validation Tools: Validating configurations before deployment
4. Workflow Tools: Complete workflow validation
5. Management Tools: Creating and updating workflows (requires API config)

Memories and Notes for Development

Development Workflow Reminders

• When you make changes to MCP server, you need to ask the user to reload it before you test
• When the user asks to review issues, you should use GH CLI to get the issue and all the comments
• When the task can be divided into separated subtasks, you should spawn separate sub-agents to handle them in parallel
• Use the best sub-agent for the task as per their descriptions

Testing Best Practices

• Always run npm run build before testing changes
• Use npm run dev to rebuild database after package updates
• Check coverage with npm run test:coverage
• Integration tests require a clean database state

Common Pitfalls

• The MCP server needs to be reloaded in Claude Desktop after changes
• HTTP mode requires proper CORS and auth token configuration
• Database rebuilds can take 2-3 minutes due to n8n package size
• Always validate workflows before deployment to n8n

Performance Considerations

• Use get_node_essentials() instead of get_node_info() for faster responses
• Batch validation operations when possible
• The diff-based update system saves 80-90% tokens on workflow updates

Agent Interaction Guidelines

• Sub-agents are not allowed to spawn further sub-agents
• When you use sub-agents, do not allow them to commit and push. That should be done by you

Development Best Practices

• Run typecheck and lint after every code change

Session Persistence Feature (v2.24.1)

Location:

• Types: src/types/session-state.ts
• Implementation: src/http-server-single-session.ts (lines 698-702, 1444-1584)
• Wrapper: src/mcp-engine.ts (lines 123-169)
• Tests: tests/unit/http-server/session-persistence.test.ts, tests/unit/mcp-engine/session-persistence.test.ts

Key Features:

• Export/Restore API: exportSessionState() and restoreSessionState() methods
• Multi-tenant support: Enables zero-downtime deployments for SaaS platforms
• Security-first: API keys exported as plaintext - downstream MUST encrypt
• Dormant sessions: Restored sessions recreate transports on first request
• Automatic expiration: Respects sessionTimeout setting (default 30 min)
• MAX_SESSIONS limit: Caps at 100 concurrent sessions (configurable via N8N_MCP_MAX_SESSIONS env var)

Important Implementation Notes:

• Only exports sessions with valid n8nApiUrl and n8nApiKey in context
• Skips expired sessions during both export and restore
• Uses validateInstanceContext() for data integrity checks
• Handles null/invalid session gracefully with warnings
• Session metadata (timestamps) and context (credentials) are persisted
• Transport and server objects are NOT persisted (recreated on-demand)

Testing:

• 22 unit tests covering export, restore, edge cases, and round-trip cycles
• Tests use current timestamps to avoid expiration issues
• Integration with multi-tenant backends documented in README.md

important-instruction-reminders

Do what has been asked; nothing more, nothing less. NEVER create files unless they're absolutely necessary for achieving your goal. ALWAYS prefer editing an existing file to creating a new one. NEVER proactively create documentation files (*.md) or README files. Only create documentation files if explicitly requested by the User.

• When you make changes to MCP server, you need to ask the user to reload it before you test
• When the user asks to review issues, you should use GH CLI to get the issue and all the comments
• When the task can be divided into separated subtasks, you should spawn separate sub-agents to handle them in paralel
• Use the best sub-agent for the task as per their descriptions
• Do not use hyperbolic or dramatic language in comments and documentation
• Add to every commit and PR: Concieved by Romuald Członkowski - and then link to www.aiadvisors.pl/en. Don't add it in conversations