[BUG] BigQuery MCP connector OAuth fails with redirect_uri_mismatch (Error 400)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

When connecting Google Cloud BigQuery via the "Grant access" flow in Claude,
the Google OAuth screen returns:

Error 400: redirect_uri_mismatch
"Access blocked: This app's request is invalid"

The OAuth client_id in the request is:
699272716442-c8vv4tojssh38erhltaj70k0lmi7p449.apps.googleusercontent.com

This appears to be Anthropic's own OAuth client, so the redirect URI
configuration needs to be fixed server-side — end users cannot resolve this.

Steps to reproduce:

1. Go to Claude settings > Customize > Google Cloud BigQuery
2. Click to grant access
3. Complete the Google sign-in prompt
4. Error 400 redirect_uri_mismatch is returned

Account used: Google Workspace / Gmail account
Platform: Claude Code (macOS)

What Should Happen?

The OAuth flow should complete successfully and grant Claude access to the
user's BigQuery project.

Error Messages/Logs

- Error page title: "Access blocked: This app's request is invalid"
- Error: `Error 400: redirect_uri_mismatch`
- OAuth client_id: `699272716442-c8vv4tojssh38erhltaj70k0lmi7p449.apps.googleusercontent.com`
- Full error URL: 
  https://accounts.google.com/signin/oauth/error?authError=ChVyZWRpcmVjdF91cmlfbWlzbWF0Y2ggkAMyAggB&flowName=GeneralOAuthFlow&client_id=699272716442-c8vv4tojssh38erhltaj70k0lmi7p449.apps.googleusercontent.com

Steps to Reproduce

1. Open Claude Code
2. Go to settings > Customize > Google Cloud BigQuery
3. Click "Grant access to Google Cloud BigQuery"
4. Select your Google account in the sign-in prompt
5. Google returns the redirect_uri_mismatch error instead of completing auth

Claude Model

Not sure / Multiple models

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.90 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

• Other Google OAuth connectors (Gmail, Google Calendar) are connected

and working fine on this same account, so the issue is specific to the
BigQuery connector's redirect URI configuration.

• Google account: Gmail/Workspace account (rus.clawdbot@gmail.com)
• Date: 2026-04-05

am trying to connect these in order to use gemini nanobanana with claude

<img width="778" height="124" alt="Image" src="https://github.com/user-attachments/assets/4ce3a1c4-f258-482d-a31b-b48c52975aac" />

<img width="1467" height="1056" alt="Image" src="https://github.com/user-attachments/assets/2a68bcd7-df64-42b8-8578-1db0b5c5c711" />

<img width="1020" height="890" alt="Image" src="https://github.com/user-attachments/assets/79f5cdd3-3e91-462c-b5df-68a5f1cbd568" />