n8n Tool Workflow with Transformer

A custom n8n node that executes workflows as AI agent tools with JavaScript output transformation capabilities.

🎯 Overview

The Tool Workflow with Transformer node is based on the official n8n ToolWorkflow node, but adds a powerful feature: the ability to transform the workflow output using custom JavaScript code before returning it to the AI agent.

This is particularly useful when you need to:

• Format workflow output for specific AI agent requirements
• Extract only relevant data from complex workflow results
• Convert data structures to match expected formats
• Summarize or aggregate workflow outputs

✨ Features

• 🤖 AI Tool Integration: Designed to work as a tool for AI agents
• 🔄 Workflow Execution: Execute any n8n workflow from database or JSON
• 🔧 Output Transformation: Transform workflow output with custom JavaScript
• 📦 Flexible Input/Output: Handle various data formats
• ⚡ Error Handling: Robust error handling and reporting

📦 Installation

Using npm

npm install n8n-nodes-tool-workflow-transformer

Local Development

1. Clone the repository:

git clone https://github.com/your-org/n8n-nodes-tool-workflow-transformer.git
cd n8n-nodes-tool-workflow-transformer

2. Install dependencies:

npm install

3. Build the project:

npm run build

4. Link to n8n:

npm link
cd /path/to/n8n
npm link n8n-nodes-tool-workflow-transformer

🔧 Node Configuration

Parameters

Tool Configuration

• Name: The name of the tool function (alphanumeric with underscores)
• Description: Description of what the tool does for the AI agent

Workflow Source

• Source: Choose between:
  • Database: Load workflow by ID from n8n database
  • Define Below: Provide workflow JSON directly

Transformation

• Transform Output: Toggle to enable/disable output transformation
• Transformation Code: JavaScript code to transform the workflow output

Transformation Variables

The transformation code has access to:

• $output: The output from the executed workflow (object or array)
• $input: The input that was sent to the workflow

📝 Usage Examples

Example 1: Extract Specific Fields

// Extract only names from an array of objects
if (Array.isArray($output)) {
  return $output.map(item => item.name).join(', ');
}
return $output.name || 'Unknown';

Example 2: Format for AI Response

// Format workflow output as a structured message
const count = Array.isArray($output) ? $output.length : 1;
return `Found ${count} results. Details: ${JSON.stringify($output, null, 2)}`;

Example 3: Aggregate Data

// Sum values from workflow output
if (Array.isArray($output)) {
  const total = $output.reduce((sum, item) => sum + (item.value || 0), 0);
  return { total, itemCount: $output.length, average: total / $output.length };
}
return $output;

Example 4: Error Handling

// Safely handle different output types
try {
  if (!$output) return 'No data received';
  
  if (Array.isArray($output)) {
    return $output.filter(item => item.status === 'active');
  }
  
  return $output.status === 'active' ? $output : null;
} catch (error) {
  return `Error processing data: ${error.message}`;
}

🏗️ Architecture

The node extends the standard n8n workflow execution with:

1. Workflow Execution: Executes the specified workflow with provided inputs
2. Output Capture: Captures the workflow output data
3. Transformation: Applies JavaScript transformation if enabled
4. Result Return: Returns the (transformed) result to the AI agent

🛠️ Development

Project Structure

n8n-nodes-tool-workflow-transformer/
├── nodes/
│   ├── ToolWorkflowWithTransformer.node.ts
│   └── toolWorkflowWithTransformer.svg
├── dist/                 # Compiled files
├── package.json
└── tsconfig.json

Available Scripts

• npm run build - Build the TypeScript code
• npm run dev - Build in watch mode
• npm run lint - Run ESLint
• npm run lintfix - Fix linting issues

🤝 Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

📄 License

MIT

🆘 Support

For issues or questions, please open an issue on GitHub.

🔗 Links

• n8n Documentation
• n8n Community Forum