Claude Cowork Now Runs Any LLM. Test It Free.

Source: The Product Compass · Author: Paweł Huryn · Date: Apr 23, 2026 · Original article

TL;DR

Anthropic quietly shipped a feature called Cowork on 3P (third-party inference) inside Claude Desktop. It lets you keep using the Claude Cowork and Claude Code environment — the agent harness with skills, plugins, MCP servers, and sub-agents — but swap the model behind it for anything: GPT-5, Grok, Gemini, open-weight models like Gemma or Kimi K2 via OpenRouter, a local model on your laptop, or your enterprise gateway (Amazon Bedrock, Google Vertex AI, Azure AI Foundry). No press release, no blog post — Paweł found it in the docs by accident, and OpenRouter's CEO confirmed it works.

The headline: you can run the full Cowork experience for free using a free OpenRouter model — no $100/$200 Max subscription required.

What "Cowork on 3P" Actually Is

A useful mental model: think of Claude Desktop as a car. The harness (Cowork, Code tab, skills, plugins, MCP, sub-agents, sandbox) is the chassis, dashboard, and seats. The LLM is the engine. Until now you had to use Anthropic's engine (Claude). With Cowork on 3P, the engine bay is now standard — drop in any compatible engine you want.

It's currently a research preview. Anthropic's docs officially target three audiences:

• Regulated industries (banks, healthcare, government) that can't legally send data to Anthropic directly.
• Companies that already route Claude through their own LLM gateway.
• Individuals on pilot/evaluation setups.

Every admin control ships on all three paths: per-user token caps, MCP allowlist, OpenTelemetry endpoint, blocking auto-updates, removing built-in tools.

OpenRouter as a gateway. OpenRouter isn't listed in Anthropic's docs, but Paweł tested it and OpenRouter's CEO Alex Atallah publicly confirmed support. That's the loophole that turns this into a free-tier story for individuals.

A nuance on Foundry: during the preview, Claude on Azure Foundry still runs on Anthropic's infrastructure. Only Bedrock and Vertex give true provider-side data residency today.

Who Should Care

Individuals — three concrete scenarios:

• You keep hitting the Max plan's weekly usage limits and want headroom.
• You'd like to try Cowork without committing to $100–$200/month.
• You're working with code or data you can't legally send to any hosted API, so you need a local model.

Enterprises — different angle, same plumbing:

• You're already on Bedrock, Vertex, or Foundry and want the Claude harness inside your existing compliance boundary.
• Your security team approves your cloud provider but not Anthropic direct.
• You need team-wide admin controls (token caps, MCP allowlist, OpenTelemetry).

How to Set It Up

1. Connect Claude Desktop to OpenRouter

No proxy needed — point Claude Desktop straight at OpenRouter.

1. Menu → Developer → Configure Third-Party Inference.
2. Set the fields:
   • Connection: Gateway
   • Gateway base URL: https://openrouter.ai/api
   • Gateway API key: your OpenRouter key
   • Gateway auth scheme: x-api-key
3. Under Sandbox & workspace, configure "Allowed egress hosts" so the agent can reach the web (use * for all sites if you trust it).
4. Click Apply locally → Relaunch now.
5. Log out, then choose Continue with Gateway.
6. You'll see "Setting up Claude's workspace…" and you can start chatting.

A free OpenRouter model that worked for Paweł: tencent/hy3-preview:free.

Local models work the same way through any OpenAI-compatible proxy — LiteLLM in front of Ollama, or Ollama's own OpenAI endpoint. That makes "fully offline Cowork" possible.

2. Import Anthropic Skills (manually)

When you're on OpenRouter, the Customize → Skills panel ships empty. The official skills (docx, pdf, pptx, xlsx, skill-creator) need to be installed by hand:

1. Download the anthropics/skills repo as a .zip.
2. Extract skills-main.zip and open the folder.
3. Zip each skill subfolder individually (e.g., the docx folder → docx.zip).
4. In Claude Desktop: Customize → Skills → Create skill → Upload a skill, and upload each .zip.

Only import skills you actually need — every loaded skill consumes context window space even when idle.

3. Import Anthropic Plugins

Same pattern, two source repos:

• Knowledge-work plugins (marketing, product-management, legal, finance): anthropics/knowledge-work-plugins
• Code-tab plugins: anthropics/claude-plugins-official

Download → extract → zip the plugin folder you want → Customize → Personal plugins → + → Create plugin → Upload plugin. Cap it at 2–3 plugins; very often 0 is the right answer.

4. Configure MCP Servers

MCP (Model Context Protocol) servers run locally — they're how the agent gets tools like Jira, Confluence, GitHub, file access, etc. Add them under Settings → Developer, which writes to a dedicated claude_desktop_config.json. The official server catalog lives at github.com/modelcontextprotocol/servers.

Example: Atlassian (Jira + Confluence) via the community mcp-atlassian server:

{
  "mcpServers": {
    "atlassian": {
      "command": "uvx",
      "args": ["mcp-atlassian"],
      "env": {
        "JIRA_URL": "https://your-domain.atlassian.net",
        "JIRA_USERNAME": "your-email@example.com",
        "JIRA_API_TOKEN": "your_api_token"
      }
    }
  }
}

5. Web Search — the one real gap

OpenRouter does not support Anthropic's native web search tool. Three workarounds:

1. Replace with an MCP. Add WebSearch to disabledBuiltinTools (so the agent doesn't get confused calling a dead tool) and install the Brave Search MCP server. Brave gives 2,000 free requests/month, then $3 per 1,000.

   {
     "mcpServers": {
       "brave-search": {
         "command": "npx",
         "args": ["-y", "@modelcontextprotocol/server-brave-search"],
         "env": { "BRAVE_API_KEY": "YOUR_API_KEY_HERE" }
       }
     }
   }
   

2. Switch provider to Vertex AI or Microsoft Foundry — both support native web search. Bedrock does not yet.
3. Wait. OpenRouter could route the web_search tool to Perplexity or similar, but that hasn't shipped.

Troubleshooting

• "Configure Third-Party Inference" missing under Menu → Developer: update Claude Desktop, restart, then enable developer mode via Help → Troubleshooting → Enable Developer Mode. Some users on corporate/Team plans have reported it's still missing — likely plan-gated or A/B rolled.
• "Local MCP servers" missing in Cowork on 3P: same fix — update + developer mode.
• Connectors show as "Unavailable": not a bug. Connectors depend on Anthropic's hosted infrastructure layer; once you go third-party, that layer is bypassed. Replace each connector with an equivalent MCP server.
• Tool calling is flaky on non-Claude models: this is real and model-dependent. Some models handle MCP calls cleanly; others fall apart on multi-step agentic flows. Best results so far come from Anthropic's own pay-per-token API models — ironic, but expected.
• Code tab settings don't match Cowork settings: Anthropic acknowledges some Cowork-on-3P config keys don't propagate identically to Code-tab sessions yet.

What This Signals (the strategic read)

Look at the controls Anthropic exposed in the Third-Party Inference panel:

• Max tokens per window (per-user soft cap)
• Allow user-added MCP servers
• OpenTelemetry collector endpoint
• Block auto-updates
• Remove built-in tools from Cowork

None of these matter to a solo user. They are admin controls. Combined with Bedrock / Vertex / Foundry support, Anthropic's framing in the docs is explicit:

Cowork on 3P is designed for organizations whose security, regulatory, or contractual requirements prevent them from sending data to Anthropic's first-party infrastructure.

The strategic implication: Claude Desktop is becoming a managed agent platform. The harness — Code, Cowork, skills, plugins, MCP, sub-agents — is what Anthropic actually wants to be the default, regardless of which model sits behind it. The model becomes commodity; the harness becomes the moat.

For individuals, the path is documented but not advertised. On a personal install with no administrator, the install instructions tell you to "enter the values supplied by your administrator" — but if there is no administrator, those fields are simply yours to fill in. That's the open door.

Bottom Line

Download Claude Desktop, point it at OpenRouter with a free model, install the skills and plugins you actually need, and you have a fully working agentic IDE — same harness as the $200/month plan — for $0. For enterprises, the same flip puts the harness inside Bedrock/Vertex/Foundry without sending data to Anthropic.

Reference docs:

• Use Claude Cowork with third-party platforms (support)
• Cowork on 3P: overview
• Cowork on 3P: installation