n8n-MCP

Instructions

Implementation Reference

• src/mcp-tools-engine.ts:52-71 (handler)

  Primary handler function for the 'full' validation mode of validate_node tool. Fetches node definition, handles missing nodes, extracts user-provided config keys to avoid false warnings, and delegates to ConfigValidator for detailed validation including errors, warnings, and suggestions.
  async validateNodeOperation(args: any) { // Get node properties and validate const node = await this.repository.getNodeByType(args.nodeType); if (!node) { return { valid: false, errors: [{ type: 'invalid_configuration', property: '', message: 'Node type not found' }], warnings: [], suggestions: [], visibleProperties: [], hiddenProperties: [] }; } // CRITICAL FIX: Extract user-provided keys before validation // This prevents false warnings about default values const userProvidedKeys = new Set(Object.keys(args.config || {})); return ConfigValidator.validate(args.nodeType, args.config, node.properties || [], userProvidedKeys); }
• src/mcp-tools-engine.ts:73-90 (handler)

  Handler function for the 'minimal' validation mode of validate_node tool. Quickly checks only for missing required fields using PropertyFilter.getEssentials.
  async validateNodeMinimal(args: any) { // Get node and check minimal requirements const node = await this.repository.getNodeByType(args.nodeType); if (!node) { return { missingFields: [], error: 'Node type not found' }; } const missingFields: string[] = []; const requiredFields = PropertyFilter.getEssentials(node.properties || [], args.nodeType).required; for (const field of requiredFields) { if (!args.config[field.name]) { missingFields.push(field.name); } } return { missingFields }; }
• src/mcp/tools.ts:112-191 (schema)

  Tool schema definition and registration in the main tools array exported for MCP server registration. Includes inputSchema with parameters (nodeType required string, config required object, mode enum full/minimal, profile enum), outputSchema with validation results structure, and description.
  { name: 'validate_node', description: `Validate n8n node configuration. Use mode='full' for comprehensive validation with errors/warnings/suggestions, mode='minimal' for quick required fields check. Example: nodeType="nodes-base.slack", config={resource:"channel",operation:"create"}`, inputSchema: { type: 'object', properties: { nodeType: { type: 'string', description: 'Node type as string. Example: "nodes-base.slack"', }, config: { type: 'object', description: 'Configuration as object. For simple nodes use {}. For complex nodes include fields like {resource:"channel",operation:"create"}', }, mode: { type: 'string', enum: ['full', 'minimal'], description: 'Validation mode. full=comprehensive validation with errors/warnings/suggestions, minimal=quick required fields check only. Default is "full"', default: 'full', }, profile: { type: 'string', enum: ['strict', 'runtime', 'ai-friendly', 'minimal'], description: 'Profile for mode=full: "minimal", "runtime", "ai-friendly", or "strict". Default is "ai-friendly"', default: 'ai-friendly', }, }, required: ['nodeType', 'config'], additionalProperties: false, }, outputSchema: { type: 'object', properties: { nodeType: { type: 'string' }, workflowNodeType: { type: 'string' }, displayName: { type: 'string' }, valid: { type: 'boolean' }, errors: { type: 'array', items: { type: 'object', properties: { type: { type: 'string' }, property: { type: 'string' }, message: { type: 'string' }, fix: { type: 'string' } } } }, warnings: { type: 'array', items: { type: 'object', properties: { type: { type: 'string' }, property: { type: 'string' }, message: { type: 'string' }, suggestion: { type: 'string' } } } }, suggestions: { type: 'array', items: { type: 'string' } }, missingRequiredFields: { type: 'array', items: { type: 'string' }, description: 'Only present in mode=minimal' }, summary: { type: 'object', properties: { hasErrors: { type: 'boolean' }, errorCount: { type: 'number' }, warningCount: { type: 'number' }, suggestionCount: { type: 'number' } } } }, required: ['nodeType', 'displayName', 'valid'] }, },
• src/mcp/tool-docs/validation/validate-node.ts:1-80 (helper)

  Detailed tool documentation including full description, parameters, returns, examples, use cases, performance notes, best practices, pitfalls, and related tools.
  import { ToolDocumentation } from '../types'; export const validateNodeDoc: ToolDocumentation = { name: 'validate_node', category: 'validation', essentials: { description: 'Validate n8n node configuration. Use mode="full" for comprehensive validation with errors/warnings/suggestions, mode="minimal" for quick required fields check.', keyParameters: ['nodeType', 'config', 'mode', 'profile'], example: 'validate_node({nodeType: "nodes-base.slack", config: {resource: "channel", operation: "create"}})', performance: 'Fast (<100ms)', tips: [ 'Always call get_node({detail:"standard"}) first to see required fields', 'Use mode="minimal" for quick checks during development', 'Use mode="full" with profile="strict" before production deployment', 'Includes automatic structure validation for filter, resourceMapper, etc.' ] }, full: { description: `**Validation Modes:** - full (default): Comprehensive validation with errors, warnings, suggestions, and automatic structure validation - minimal: Quick check for required fields only - fast but less thorough **Validation Profiles (for mode="full"):** - minimal: Very lenient, basic checks only - runtime: Standard validation (default) - ai-friendly: Balanced for AI agent workflows - strict: Most thorough, recommended for production **Automatic Structure Validation:** Validates complex n8n types automatically: - filter (FilterValue): 40+ operations (equals, contains, regex, etc.) - resourceMapper (ResourceMapperValue): Data mapping configuration - assignmentCollection (AssignmentCollectionValue): Variable assignments - resourceLocator (INodeParameterResourceLocator): Resource selection modes`, parameters: { nodeType: { type: 'string', required: true, description: 'Node type with prefix: "nodes-base.slack"' }, config: { type: 'object', required: true, description: 'Configuration object to validate. Use {} for empty config' }, mode: { type: 'string', required: false, description: 'Validation mode: "full" (default) or "minimal"' }, profile: { type: 'string', required: false, description: 'Validation profile for mode=full: "minimal", "runtime" (default), "ai-friendly", "strict"' } }, returns: `Object containing: - nodeType: The validated node type - workflowNodeType: Type to use in workflow JSON - displayName: Human-readable node name - valid: Boolean indicating if configuration is valid - errors: Array of error objects with type, property, message, fix - warnings: Array of warning objects with suggestions - suggestions: Array of improvement suggestions - missingRequiredFields: (mode=minimal only) Array of missing required field names - summary: Object with hasErrors, errorCount, warningCount, suggestionCount`, examples: [ '// Full validation with default profile\nvalidate_node({nodeType: "nodes-base.slack", config: {resource: "channel", operation: "create"}})', '// Quick required fields check\nvalidate_node({nodeType: "nodes-base.webhook", config: {}, mode: "minimal"})', '// Strict validation for production\nvalidate_node({nodeType: "nodes-base.httpRequest", config: {...}, mode: "full", profile: "strict"})', '// Validate IF node with filter\nvalidate_node({nodeType: "nodes-base.if", config: {conditions: {combinator: "and", conditions: [...]}}})' ], useCases: [ 'Validate node configuration before adding to workflow', 'Quick check for required fields during development', 'Pre-production validation with strict profile', 'Validate complex structures (filters, resource mappers)', 'Get suggestions for improving node configuration' ], performance: 'Fast validation: <50ms for minimal mode, <100ms for full mode. Structure validation adds minimal overhead.', bestPractices: [ 'Always call get_node() first to understand required fields', 'Use mode="minimal" for rapid iteration during development', 'Use profile="strict" before deploying to production', 'Pay attention to warnings - they often prevent runtime issues', 'Validate after any configuration changes' ], pitfalls: [ 'Empty config {} is valid for some nodes (e.g., manual trigger)', 'mode="minimal" only checks required fields, not value validity', 'Some warnings may be acceptable for specific use cases', 'Credential validation requires runtime context' ], relatedTools: ['get_node', 'validate_workflow', 'n8n_autofix_workflow'] } };