BoxConnect multiple Box accounts to Claude
An MCP connection to Box carries one account. If you hold an account in your own enterprise and one in a client's, one connection is not enough. Switching means authorizing again, and the previous account is gone until you switch back. Handling several accounts of the same connector is an open request on GitHub (anthropics/claude-code #27302).
This guide uses ProxyLoom to put several Box accounts behind a single MCP connection, so Claude can work in any of them and you say which one by name. It takes about five minutes, with no app registration and no JSON config.
What you end up with
One connector in Claude called ProxyLoom. Behind it, each Box account you connected, with a label you chose (for example work, client-a, client-b). Every Box tool Claude sees carries an account argument, so "find the contract folder in client-a" and "upload the summary to work" both work in the same conversation, without disconnecting anything.
1. Sign up for ProxyLoom
Create an account at https://app.proxyloom.dev/sign-up.
2. Connect each Box account
Signing in puts you on the Connections screen. Click + Connect an account, pick Box, and click Authenticate and connect →. Box's own consent screen opens; approve the access. Repeat for each account you want. Each one becomes a separate connection with its own token.
Back on the Connections screen, give each connection a label: click Add a label in that connection's Label column. The label is the name you will use when you talk to Claude, so use what you already call it:
work,client-a,client-b. Without a label ProxyLoom falls back to the name Box reports for the connected account.3. Add ProxyLoom to Claude
In Claude, open Settings → Connectors and click Add (top right). The Add custom connector dialog opens: give it a name — ProxyLoom — paste your ProxyLoom URL as the MCP server URL, and continue. The URL sits in the MCP Endpoint bar at the top of ProxyLoom's Connections screen, with a copy button next to it.
Continuing opens ProxyLoom's authorization in your browser: sign in once and approve, and the connector is authorized. That is the only connection Claude holds.
This works the same in the Claude desktop app, claude.ai and Claude Code. Any client that speaks Streamable HTTP MCP and OAuth 2.1 (Codex, Cursor, ChatGPT) is set up much the same way, with the same URL.
4. Use it
Ask Claude to list the connected accounts to confirm everything is there:
Which Box accounts do you have?
Claude asks ProxyLoom and answers with the labels. From then on, name the account in the request:
Find the contracts folder in client-a and summarize the latest version.
Upload that summary to work and create a shared link.
If a request is ambiguous, Claude asks which account you mean rather than guessing. Which account was used is recorded in ProxyLoom's audit log, so you can check afterwards.
Notes
- There is nothing to set up on the Box side. Each connection carries only what you approved on Box's consent screen: browsing, searching and reading files and folders, uploading files and new versions, creating, copying, moving and updating files and folders, managing metadata, comments, tasks, shared links and collaborations, and asking Box AI about files and hubs. All of it stays within what the connected user may access in Box. You can revoke that grant at any time — delete the connection on ProxyLoom's Connections screen, or remove ProxyLoom in the authorized apps of your Box account.
- Adding a account later does not mean repeating step 3, Add ProxyLoom to Claude — that one is done once and never again. Connect it on ProxyLoom's Connections screen, and Claude sees it from then on.