n8n Workflow Development

Instructions

Build n8n workflows programmatically using the MCP SDK. Follow this mandatory sequence:

SDK build sequence:

1. get_sdk_reference — learn SDK patterns, coding guidelines, and design guidance
2. search_nodes — discover nodes for services (e.g., “gmail”, “slack”) and utilities (“set”, “if”, “merge”, “code”); note discriminators (resource/operation/mode)
3. get_node_types — get exact TypeScript parameter definitions for ALL nodes including discriminators; never guess parameter names
4. validate_workflow — validate full code before deployment; fix errors and re-validate until clean
5. create_workflow_from_code — save the workflow to n8n with a short description
6. publish_workflow — activate the workflow; required after every create or update

Expression engine safe patterns:

• Use || for fallbacks, never ?? (nullish coalescing is unsupported in n8n expressions)
• Use $execution.id for memory session keys to ensure uniqueness per run
• Keep jsonBody expressions simple — avoid nested ternaries or complex logic
• Reference previous node output via $('Node Name').item.json.fieldName

Credential management:

• Create credentials via REST API: POST /api/v1/credentials with type, name, and data
• Reference credentials in nodes by credential type and ID
• Never hardcode secrets in workflow JSON — always use credential references

Webhook design:

• Use Webhook trigger node for inbound HTTP; set path, method, and authentication
• Return responses via “Respond to Webhook” node for synchronous flows
• For async: acknowledge immediately, process in background branch

Workflow patterns:

• Sequential: linear node chain for step-by-step processing
• Parallel: split with multiple outputs from a single node; merge results downstream
• Router: Switch node for conditional branching by field value or expression

Updating existing workflows:

• Batch patch via PUT /api/v1/workflows/{id} with the full workflow JSON body
• After every PUT, call publish_workflow to re-activate — updates are inactive until published