Connect docs
Connect 3V3 to your AI app
MCP, the Model Context Protocol, is how an AI app uses tools that live somewhere else. 3V3 is one: your app draws the outline, places the parts, routes the copper, runs the checks and exports the files, and you watch it on app.3v3.dev.
The address
https://mcp.3v3.devTwo ways in. Sign in: paste the address into your app, sign in to 3V3 and press Allow (OAuth, as the MCP standard describes it); nothing to install and no key to copy. A key: for scripts and clients that can't sign in.
Pick your app
| App | Sign in | Key | Source |
|---|---|---|---|
| Claude (claude.ai and Claude Desktop) | Yes | Yes | Tried with 3V3 |
| Claude Code (the terminal) | Yes | Yes | Its own docs, 8 October 2026 |
| Cursor | Yes | Yes | Its own docs, 8 October 2026 |
| ChatGPT | Yes | — | Its own docs, 8 October 2026 |
| VS Code (GitHub Copilot, agent mode) | Yes | Yes | Its own docs, 8 October 2026 |
| Windsurf, now Devin Desktop | Yes | Yes | Its own docs, 8 October 2026 |
| Codex CLI (OpenAI) | Yes | Yes | Its own docs, 8 October 2026 |
| Gemini CLI (Google) | Yes | Yes | Its own docs, 8 October 2026 |
| Scripts and other clients | — | Yes | Our own docs |
“Tried with 3V3” means we connected it ourselves. “Its own docs” means the steps follow that app's documentation as it read on 8 October 2026, linked on its page; apps move their menus, so that page is the one to trust.
If it stops
What 3V3 says, word for word, and what to do.
| When | 3V3 says | Do this |
|---|---|---|
| Your app says it needs to sign in, or 401 | This endpoint needs your API key: send it as “Authorization: Bearer 3v3_dev_…”. Make one on the Connect an agent page (/connect). | An app that signs in does this for you: let it open 3V3's page. A script sends a key. |
| You disconnected the app | That app was disconnected from your 3V3 account. Connect it again to carry on. | Connect it again (the same steps); Disconnect on the Connect page did exactly this. |
| The sign-in ran out | That sign-in has expired; your app gets a new one on its own. | Normally the app refreshes it by itself. If it keeps saying so, sign in again from the app. |
| A revoked key | That key was revoked. Make a new one at POST /api/keys. | Make a new key on app.3v3.dev/connect and put it where the old one was. |
| Too fast | Slow down: this key has sent 120 messages in the last minute, and the limit is 120 a minute. Wait a minute and carry on. | Each key or app may send 120 messages a minute; wait a minute. |
| Too many boards today | This key has made 50 boards in the last 24 hours, and the limit is 50 a day. Carry on with one of them, or wait. | Each key or app may make 50 boards a day through MCP; your plan has its own monthly count too. |
| A wrong address | This address is 3V3's MCP endpoint: https://mcp.3v3.dev | Use the address exactly, with nothing after it. Opened in a browser it answers 405: it only speaks MCP. |