Google Drive connector cannot access files shared with the user (appears limited to drive.file scope)

### What happened?

The Claude.ai Google Drive connector can only reach files it created itself. Files that were shared with my account by a colleague are invisible to it, even with Editor rights.

Reproduced in Claude Cowork on 2026-08-27 against a Google Sheet owned by an account in a different Workspace domain and shared directly with my account (Editor). The file opens and edits normally for me in the Drive web UI.

Results:
- get_file_metadata with the file ID -> "Requested entity was not found"
- copy_file with the same file ID -> "Requested entity was not found" (a direct API call by ID, so this is not a search-indexing problem)
- search_files with sharedWithMe = true -> empty result
- search_files with owner = 'me' -> 2 files, both of which were created by Claude itself in earlier sessions
- search_files by the exact file title -> empty result

The pattern (reads only what the app created, sees nothing shared) matches an OAuth grant limited to the drive.file scope rather than drive.readonly.

### What did you expect to happen?

Per the help centre article "Use Google Workspace connectors": "Claude mirrors your existing permissions - you cannot access information you do not already have access to in Google Workspace."

On that basis a file shared with my account with Editor rights should be readable by the connector. Either the connector should receive a scope that matches the documented behaviour, or there should be a file-picker so a user can explicitly authorise individual shared files - and the documentation should state the actual limitation.

### Steps to reproduce

1. Connect the Google Drive connector in Claude.ai and grant every permission requested.
2. Have a colleague in another Workspace domain share a Google Sheet directly with your account, with Editor rights. Not a Shared Drive, not link-only.
3. Confirm in the Drive web UI that you can open and edit it.
4. In Claude, ask the Drive connector to read that file by its ID -> "Requested entity was not found".
5. Ask it to list files with sharedWithMe = true -> empty.
6. Disconnect the connector completely, reconnect it, and approve every permission on the Google consent screen. A new token is definitely issued (an additional Google connector appeared in the same session). Repeat steps 4-5 -> identical results.

### Area

MCP Connector (adding/managing servers)

### MCP Server (if applicable)

Google Drive (Claude.ai connector)

### Error messages or logs

```shell
Client: Claude desktop app, Cowork mode. Date: 2026-08-27.
File owner: an account in a different Google Workspace domain. Sharing: direct, Editor. Not a Shared Drive, not link-only.

Impact: our commercial pipeline lives in a sheet owned by a colleague. Every workflow that should read it has to fall back to a CSV export or to browser automation, which defeats the purpose of the connector.

Possibly related, reported from the Google side: Google Drive Community thread 418185709, "Claude for Google Drive - Only 1 of 3 OAuth Scopes Being Granted Despite Trusted App Status".
```

### Additional context

_No response_