n8n workflows with LLM classification

Pain

Classic integrations cost weeks: a separate service per connection, manual error handling, no overview of running flows. LLMs add another layer that doesn't fit cleanly into hard-wired pipelines.

Solution

• ◆Receive every incoming event through a single webhook endpoint.
• ◆Validate the payload structurally (Zod-style JSON-schema checks) before any LLM is called.
• ◆Let Claude do the classification (heat score, intent, spam detection) and store the result in the CRM.
• ◆Let Gemini draft a personalized reply that goes out via Gmail.
• ◆Mirror an error branch under the success path: any node can fall through to a failure path that ends in a Telegram alert, no silent failures.

How it works

1. 01
   Webhook (POST /lead)

   Entry point for forms, external tools, mail filters.
2. 02
   Validate ({ })

   Structural check: missing fields and wrong types are rejected immediately.
3. 03
   Claude · classify

   LLM scores heat (Hot/Warm/Cold) and assigns an intent tag.
4. 04
   Save to CRM

   Lead is written into Sheets or Notion with classification.
5. 05
   Gemini · draft reply

   Personalized reply draft based on classification plus lead context.
6. 06
   Send via Gmail

   Reply goes out, CRM entry is flipped to 'contacted'.
7. 07
   Error branch

   On node failure, the parallel path takes over, logging into a Telegram alert.

Outcome

New integrations are built as a workflow instead of a separate service. Workflows run in production; failures become visible instead of disappearing.

Why this stack

n8n

Visual workflow editor with production features (retry, logging, versioning).

Claude

Classification with traceable reasoning, relevant for CRM audits. Internal funnel: for clients we swap in an open-source model on our own GPU or a provider their data protection team approves.

Gemini

Fast and cost-effective generation of personalized reply drafts. For clients the same provider choice applies as for classification.

Webhooks

Universal adapter: almost any tool can POST.