n8n MCP Server

Instructions

Implementation Reference

• src/n8n-client.ts:441-459 (handler)

  Core implementation of connect_nodes tool. Updates the workflow's connections by linking the output of the 'from' node to the input of the 'to' node, with optimistic concurrency via performWorkflowUpdate.
  async connectNodes(request: ConnectNodesRequest): Promise<ConnectNodesResponse> { await this.performWorkflowUpdate(request.workflowId, (workflow) => { const fromNode = workflow.nodes.find((node) => node.id === request.from.nodeId); const toNode = workflow.nodes.find((node) => node.id === request.to.nodeId); if (!fromNode) throw new Error(`Source node ${request.from.nodeId} not found in workflow ${request.workflowId}`); if (!toNode) throw new Error(`Target node ${request.to.nodeId} not found in workflow ${request.workflowId}`); const connections: any = workflow.connections as any; if (!connections[fromNode.name]) connections[fromNode.name] = {}; const fromMain = connections[fromNode.name].main || []; connections[fromNode.name].main = fromMain; const outputIndex = request.from.outputIndex ?? 0; if (!fromMain[outputIndex]) fromMain[outputIndex] = []; const connection = { node: toNode.name, type: 'main', index: request.to.inputIndex ?? 0 }; const exists = fromMain[outputIndex].some((conn: any) => conn.node === connection.node && conn.index === connection.index); if (!exists) fromMain[outputIndex].push(connection); }); return { ok: true }; }
• src/index.ts:589-598 (handler)

  MCP server handler method that receives the tool call and delegates to N8nClient.connectNodes, formatting the response.
  private async handleConnectNodes(args: ConnectNodesRequest) { const result = await this.n8nClient.connectNodes(args); return { content: [ { type: 'text', text: JSON.stringify(jsonSuccess(result), null, 2), }, ], };
• src/index.ts:213-215 (registration)

  Tool registration in the listTools handler, defining name, description, and input schema.
  { name: 'connect_nodes', description: 'Connect two nodes in an n8n workflow', inputSchema: { type: 'object', properties: { workflowId: { oneOf: [{ type: 'string' }, { type: 'number' }] }, from: { type: 'object', properties: { nodeId: { type: 'string' }, outputIndex: { type: 'number' } }, required: ['nodeId'] }, to: { type: 'object', properties: { nodeId: { type: 'string' }, inputIndex: { type: 'number' } }, required: ['nodeId'] } }, required: ['workflowId', 'from', 'to'] } }, { name: 'delete_node', description: 'Delete a node from an n8n workflow', inputSchema: { type: 'object', properties: { workflowId: { oneOf: [{ type: 'string' }, { type: 'number' }] }, nodeId: { type: 'string' } }, required: ['workflowId', 'nodeId'] } }, { name: 'set_node_position', description: 'Set the position of a node in an n8n workflow', inputSchema: { type: 'object', properties: { workflowId: { oneOf: [{ type: 'string' }, { type: 'number' }] }, nodeId: { type: 'string' }, x: { type: 'number' }, y: { type: 'number' } }, required: ['workflowId', 'nodeId', 'x', 'y'] } },
• src/types.ts:214-228 (schema)

  TypeScript interfaces defining the input (ConnectNodesRequest) and output (ConnectNodesResponse) shapes for the connect_nodes tool.
  export interface ConnectNodesRequest { workflowId: string | number; from: { nodeId: string; outputIndex?: number; }; to: { nodeId: string; inputIndex?: number; }; } export interface ConnectNodesResponse { ok: true; }
• src/index.ts:319-320 (registration)

  Tool dispatch routing in the CallToolRequest handler switch statement.
  case 'connect_nodes': return await this.handleConnectNodes(request.params.arguments as unknown as ConnectNodesRequest);