n8n MCP Server

Instructions

Implementation Reference

• src/n8n-client.ts:426-439 (handler)

  Primary handler function that implements the core logic for updating a node: locates the node by ID in the workflow, merges new params/credentials/name/typeVersion, and performs an atomic workflow update with ETag concurrency control.
  async updateNode(request: UpdateNodeRequest): Promise<UpdateNodeResponse> { await this.performWorkflowUpdate(request.workflowId, (workflow) => { const nodeIndex = workflow.nodes.findIndex((node) => node.id === request.nodeId); if (nodeIndex === -1) { throw new Error(`Node with id ${request.nodeId} not found in workflow ${request.workflowId}`); } const node = workflow.nodes[nodeIndex]; if (request.params !== undefined) node.parameters = { ...node.parameters, ...request.params }; if (request.credentials !== undefined) node.credentials = { ...node.credentials, ...request.credentials }; if (request.name !== undefined) node.name = request.name; if (request.typeVersion !== undefined) node.typeVersion = request.typeVersion; }); return { nodeId: request.nodeId }; }
• src/index.ts:212-212 (registration)

  Tool registration in the ListTools response, defining name, description, and input schema.
  { name: 'update_node', description: 'Update an existing node in an n8n workflow', inputSchema: { type: 'object', properties: { workflowId: { oneOf: [{ type: 'string' }, { type: 'number' }] }, nodeId: { type: 'string' }, params: { type: 'object' }, credentials: { type: 'object' }, name: { type: 'string' }, typeVersion: { type: 'number' } }, required: ['workflowId', 'nodeId'] } },
• src/types.ts:201-208 (schema)

  TypeScript interface defining the input parameters for the update_node tool.
  export interface UpdateNodeRequest { workflowId: string | number; nodeId: string; params?: Record<string, any>; credentials?: Record<string, string>; name?: string; typeVersion?: number; }
• src/index.ts:553-562 (handler)

  MCP server handler method that receives tool calls for 'update_node' and delegates to N8nClient.updateNode, formatting the success response.
  private async handleUpdateNode(args: UpdateNodeRequest) { const result = await this.n8nClient.updateNode(args); return { content: [ { type: 'text', text: JSON.stringify(jsonSuccess(result), null, 2), }, ], };
• src/n8n-client.ts:384-406 (helper)

  Helper method used by updateNode for atomic workflow updates with ETag-based optimistic concurrency and exponential backoff retries on conflicts.
  private async performWorkflowUpdate( workflowId: string | number, operation: (workflow: N8nWorkflow) => void, maxRetries: number = 3, ): Promise<void> { let retries = 0; while (retries < maxRetries) { try { const { workflow, etag } = await this.getWorkflowWithETag(workflowId); operation(workflow); await this.updateWorkflow(workflowId, workflow, etag || undefined); return; } catch (error: any) { const message = error?.message || ''; if (message.includes('Precondition failed') && retries < maxRetries - 1) { retries++; await new Promise((resolve) => setTimeout(resolve, Math.pow(2, retries) * 100)); continue; } throw error; } } }