mcp-n8n-builder

Instructions

Implementation Reference

• src/tool-handlers/workflow-tools.ts:418-475 (handler)

  The handler function that implements the core logic for the 'activate_workflow' MCP tool. It validates the input arguments, calls the N8nApiClient to activate the workflow, formats the response, and handles specific errors like missing triggers with helpful guidance.

   * Handles the activate_workflow tool
   */
  export async function handle_activate_workflow(
  	api_client: N8nApiClient,
  	args: any,
  ) {
  	if (!args.id) {
  		throw new McpError(
  			ErrorCode.InvalidParams,
  			'Workflow ID is required',
  		);
  	}
  
  	try {
  		const result = await api_client.activate_workflow(args.id);
  		return {
  			content: [
  				{
  					type: 'text',
  					text: `Successfully activated workflow "${result.name}" (ID: ${args.id})`,
  				},
  			],
  		};
  	} catch (error: any) {
  		// Check for common activation errors
  		if (error.message && error.message.includes('trigger')) {
  			// This is likely an error about missing trigger nodes
  			const core_principles =
  				WORKFLOW_COMPOSITION_GUIDE.core_principles;
  
  			return {
  				content: [
  					{
  						type: 'text',
  						text:
  							`Error activating workflow: ${error.message}\n\n` +
  							`Note: Only workflows with automatic trigger nodes (Schedule, Webhook, etc.) can be activated. ` +
  							`Workflows with only manual triggers cannot be automatically activated.\n\n` +
  							`Here are some core principles for workflow composition:\n${core_principles}`,
  					},
  				],
  				isError: true,
  			};
  		}
  
  		return {
  			content: [
  				{
  					type: 'text',
  					text: `Error activating workflow: ${
  						error.message || String(error)
  					}`,
  				},
  			],
  			isError: true,
  		};
  	}
  }

• src/tool-handlers/index.ts:218-233 (registration)

  Tool registration in the list_tools handler, defining the name, description, and input schema for 'activate_workflow'.

  {
  	name: 'activate_workflow',
  	description:
  		'Activates a workflow by its ID, enabling it to run automatically based on its trigger (schedule, webhook, etc.). Note that only workflows with automatic trigger nodes can be activated - workflows with only manual triggers cannot be activated.',
  	inputSchema: {
  		type: 'object',
  		properties: {
  			id: {
  				type: 'string',
  				description:
  					'ID of the workflow to activate - can be obtained from list_workflows',
  			},
  		},
  		required: ['id'],
  	},
  },

• src/tool-handlers/index.ts:330-331 (registration)

  Dispatch logic in the call_tool handler that routes 'activate_workflow' calls to the handle_activate_workflow function.

  case 'activate_workflow':
  	return await handle_activate_workflow(api_client, args);

• src/n8n-api-client.ts:160-162 (helper)

  Supporting helper method in the N8nApiClient class that makes the actual HTTP POST request to the n8n API to activate a workflow by ID.

  async activate_workflow(id: string): Promise<any> {
  	return this.request<any>('POST', `/workflows/${id}/activate`);
  }