drive-update-mcp

A small remote MCP server that gives Claude one capability the built-in Google Drive connector is missing: updating an existing Drive file in place.

When Claude calls update_drive_file, the file keeps the same file ID, the same shareable link, and Drive retains the previous version in its revision history. No duplicates, no broken links.

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How it works

Claude (claude.ai / app)  ──►  this MCP server (on Render)  ──►  Google Drive API
                                                                   files.update()  ← overwrites in place

• Claude connects to the server from Anthropic's cloud using the Streamable HTTP MCP transport.
• The server authenticates to Google Drive with a service account — no interactive Google login to manage. You grant it access to a file by sharing that file (or its folder) with the service-account's email address.

Tools exposed

Tool	What it does
update_drive_file	Overwrite an existing file's contents by fileId (in place).
find_files	Search by name to resolve a file's fileId.
create_drive_file	Create a new file from base64 content (optionally in a folder).
list_revisions	Show a file's revision history.

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Prerequisites

• A Google account with Google Drive.
• A Google Cloud project (free).
• A Render account (free tier is fine) — or any Node host that gives you an HTTPS URL.
• A Claude Pro, Max, Team, or Enterprise plan (custom connectors are not on Free).

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Setup

Part A — Create the Google service account

1. Go to the Google Cloud Console → create or pick a project.
2. APIs & Services → Library → enable the Google Drive API.
3. IAM & Admin → Service Accounts → Create service account (any name, e.g. drive-updater).
4. Open the service account → Keys → Add key → Create new key → JSON. A .json file downloads.
5. Note the service account's email (looks like drive-updater@your-project.iam.gserviceaccount.com).

Part B — Give the service account access to your file

The service account can only touch files that are shared with it.

• In Google Drive, share the target file (or, easier, the folder that holds it) with the service-account email from step A5, with Editor permission.
• Do this once per file/folder you want Claude to be able to update.

Tip: keep all the docs Claude manages in one folder and share just that folder.

Part C — Deploy to Render

1. Push this folder to a GitHub repo (or use Render's "deploy from local" / blueprint).
2. In Render: New → Web Service → point it at the repo. render.yaml is included, so Render will pick up the build/start commands automatically. Otherwise set:
   • Build command: npm install
   • Start command: npm start
3. Add two Environment Variables:
   • GOOGLE_SERVICE_ACCOUNT_JSON → paste the entire contents of the JSON key file from Part A4.
   • MCP_AUTH_TOKEN → a long random string you invent (this protects the endpoint).
4. Deploy. When it's live, confirm https://YOUR-APP.onrender.com/health returns {"ok":true,...}.

Part D — Connect it to Claude

1. In Claude: Settings → Connectors → "+" → Add custom connector (on Pro/Max you may need to enable connector/developer features first).
2. Name: Drive Update
3. URL: https://YOUR-APP.onrender.com/mcp?token=YOUR_MCP_AUTH_TOKEN (the ?token=... is how the server authorises the call — use the same value as MCP_AUTH_TOKEN).
4. Click Add. Leave the OAuth fields blank.
5. In a conversation, enable it via the "+" → Connectors toggle.

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Using it with Claude

Once connected, the typical flow is:

1. You ask Claude to make changes to a document it produces.
2. Claude builds the updated file, then calls find_files (to get the fileId from the name) or you paste the Drive link, and update_drive_file to overwrite it in place.

For the very first upload, the file has to exist in Drive (so it has an ID to update). Either upload it once yourself, or have Claude call create_drive_file once; after that, every change is an in-place update_drive_file.

Note on size: the new content is passed to the tool base64-encoded, so very large files mean large tool calls. For typical Office documents (well under a few MB) this is fine.

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Security notes

• The MCP_AUTH_TOKEN in the URL is what stops anyone else from driving your server. Treat that URL like a password; rotate the token if it leaks.
• The service account can reach only the files/folders you explicitly shared with it. It cannot see the rest of your Drive.
• For a hardened setup you can replace the token gate with a full OAuth flow (Claude supports OAuth + Dynamic Client Registration); that's a later upgrade, not needed to start.

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Local development

npm install
# put GOOGLE_SERVICE_ACCOUNT_JSON and MCP_AUTH_TOKEN in your shell env (or a .env loader)
npm start
# health check:
curl localhost:3000/health

drive-update-mcp-