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n8n workflows are best monitored via Muster’s HTTP webhook. The n8n scanner requires network access to your n8n instance and won’t work for locally-hosted setups.

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Overview

Add a single HTTP Request node at the end of your n8n workflow. This sends quality signals to Muster after every execution.

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Setup

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1. Register the workflow in Muster

In your Muster dashboard → Add Agent:
  • Name: your workflow name (e.g. invoice-processing-n8n)
  • Framework: N8N
  • Owner email and department

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2. Add an HTTP Request node

In your n8n workflow, add an HTTP Request node as the last step: Node settings:
SettingValue
MethodPOST
URLhttps://app.getmuster.io/api/v1/jobs/{{ $now.toMillis() }}/quality
AuthenticationNone
Send BodyEnabled
Body Content TypeJSON
JSON body: 
{
  "agent_id": "invoice-processing-n8n",
  "job_id": "{{ $now.toMillis() }}",
  "overall_passed": true,
  "checks": [
    {
      "check_id": "output_not_empty",
      "severity": "HIGH",
      "passed": {{ $json.output ? true : false }}
    }
  ]
}

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3. Handle errors

To report failures, use an Error Trigger node connected to a second HTTP Request node: 
{
  "agent_id": "invoice-processing-n8n",
  "job_id": "{{ $now.toMillis() }}",
  "overall_passed": false,
  "checks": [
    {
      "check_id": "output_not_empty",
      "severity": "HIGH",
      "passed": false,
      "message": "{{ $json.message }}"
    }
  ]
}

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Dynamic checks

For more detailed monitoring, build the checks array dynamically using n8n’s Code node before the HTTP Request: 
// Code node
const output = $input.first().json;

const checks = [
  {
    check_id: "output_not_empty",
    severity: "HIGH",
    passed: !!output.result
  },
  {
    check_id: "required_fields_present",
    severity: "HIGH",
    passed: !!(output.vendor && output.total && output.date),
    expected: "vendor,total,date",
    actual: Object.keys(output).filter(k => ["vendor","total","date"].includes(k)).join(",")
  }
];

return [{
  json: {
    agent_id: "invoice-processing-n8n",
    job_id: $now.toMillis().toString(),
    overall_passed: checks.every(c => c.passed),
    checks
  }
}];
Then connect this node’s output to an HTTP Request node posting to Muster.

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Tracking token usage

If your n8n workflow calls OpenAI or Anthropic, pass token counts to Muster for cost tracking: 
{
  "agent_id": "invoice-processing-n8n",
  "job_id": "{{ $now.toMillis() }}",
  "overall_passed": true,
  "token_input": {{ $node["OpenAI"].data.usage.prompt_tokens }},
  "token_output": {{ $node["OpenAI"].data.usage.completion_tokens }},
  "model": "gpt-4o",
  "checks": []
}