n8n Anthropic Writer-Critic Drafting Workflow + Google Sheets

Draft smarter with n8n: an Anthropic Writer-Critic workflow that iterates until your rubric says “approved”

This n8n workflow generates a draft using an Anthropic chat model, then critiques and revises it against your house rules and rubric—automatically looping until it meets an approval threshold or stops for defined reasons. Each run is logged to Google Sheets, with an optional webhook notification when it finishes.

What this workflow does

• Starts when you run it manually or via an n8n Chat trigger.
• Loads configuration inputs: house rules, rubric, approval score, maximum rounds, and a default brief; initializes loop state using your brief.
• Writes with an Anthropic writer agent to produce or revise a draft and return a structured result (draft plus self-assessment and any placeholders needing human input).
• Critiques with an Anthropic critic agent to score the draft and return structured outcomes: must-fix items, optional improvements, and any rule violations.
• Decides to continue using three stop conditions: (1) approved with no must-fix items, (2) round limit reached, or (3) score stalled across recent rounds.
• Generates revision instructions for the next round by converting the critique into actionable updates.
• Finalizes output with exit reason, final draft, remaining must-fix items/human inputs, and a score history.
• Logs results to Google Sheets and can POST a completion notice to a configured webhook URL.

Use cases

• Iteratively refine blog posts, product pages, or SOP drafts to match internal brand and quality standards.
• Enforce consistent compliance and formatting using house rules + a scored rubric.
• Run an approval-gated writing pipeline and keep an auditable ledger of draft iterations in Google Sheets.

Technical details

• Integrations/nodes reflected in the workflow: if, set, code, sticky note, http request, and Google Sheets.
• Relies on an Anthropic chat model (writer + critic agents) to draft, critique, score, and produce structured revision instructions.

Setup note: add your Anthropic (or compatible) chat model credentials to the workflow (details continue after the provided excerpt).