Run Coworker desktop agents cheaply with GPT-5.6 Luna on OpenRouter

Melvin Vivas · X post · 2026-09-11 · Open on X

Topics: AI Agents, Tool Use & MCP, LLM Fundamentals, AI Dev Tools & Productivity · Level: intermediate

Summary

The creator recommends the GPT-5.6 Luna model for agent 'coworker bots' because it is very cheap through OpenRouter. He links his open-source Coworker desktop app, where AI agents do work for you using local or cloud models.

Key points

• GPT-5.6 Luna is a low-cost model that works well for agent bots.
• Using it through OpenRouter keeps costs very low.
• Coworker (donvito/coworker) is a desktop app where AI agents do tasks for you.
• Coworker supports both local and cloud models.

Resources mentioned

• Coworker (donvito/coworker) · repo · github.com · free
  The creator's local-first desktop app where you pick an AI coworker and have it produce work such as invoices as finished PDFs.
  Also in: Claude Opus 5.5 for Video Making: Creator's Showcase Thread (Coworker) (Melvin Vivas on X · notes), Coworker: free open-source desktop AI coworker app (Melvin Vivas on X · notes), Coworker: Open-Source Desktop App for AI Agents (Melvin Vivas on X · notes), Using Devin AI to Test the Coworker Desktop App on Windows (Melvin Vivas on X · notes) and 38 more
• OpenRouter · tool · openrouter.ai · free
  A single OpenAI-compatible API that routes requests to hundreds of models from many providers, with one bill and model fallbacks.
  Also in: Customizing Your Coding Setup with Pi Coding Agent Extensions (Melvin Vivas on X · notes), The Jev model is now on OpenRouter (Melvin Vivas on X · notes), Kev-4B model, an alternative to Jev, now available on OpenRouter (Melvin Vivas on X · notes), Space Bunny Alpha: stealth 1M-context flash model on OpenRouter (Melvin Vivas on X · notes) and 42 more
• GPT 5.6 Luna · tool · openai.com · paid
  The OpenAI model used inside Codex for the demo. The transcript gives the variant name as 'Soul', which is unclear.
  Also in: Set Codex subagent model and reasoning to save usage limits (Melvin Vivas on X · notes), Use GPT-5.6 Luna in Codex for Terminal Tasks (Melvin Vivas on X · notes), Match Reasoning Effort to Task Length in Codex (Astra/Sol) (Melvin Vivas on X · notes), Codex Config: GPT-6 Astra Orchestrator + GPT-5.6 Luna Subagents at Medium (Melvin Vivas on X · notes) and 24 more

Try this

• Try GPT-5.6 Luna through OpenRouter as a cheap model for your Coworker agents.