# MCP Allowlist Request - Google Gemini Spark

**URL:** <https://developer.squareup.com/forums/t/mcp-allowlist-request-google-gemini-spark/27902>\
**Category:** MCP\
**Created:** [September 21, 2026, 3:32am UTC](https://developer.squareup.com/forums/t/mcp-allowlist-request-google-gemini-spark/27902 "2026-09-21T03:32:30Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![fixlaptop124](https://avatars.discourse-cdn.com/v4/letter/f/e19adc/32.png) [@fixlaptop124](https://developer.squareup.com/forums/u/fixlaptop124)\
**Post date:** [September 21, 2026, 3:32am UTC](https://developer.squareup.com/forums/t/mcp-allowlist-request-google-gemini-spark/27902/1 "2026-09-21T03:32:30Z")

</div>

Hello,  
I am trying to connect Square’s hosted MCP server to Google Gemini Spark using:

`https://mcp.squareup.com/mcp`

Client: Google Gemini Spark custom connected app  
OAuth redirect URI:  
`https://oauth-redirect.googleusercontent.com/r/user_bound_custom-mcp-107303354335300565420-mcp_squareup_com`

I created a Square production developer application, configured the redirect URI, and entered the Production Application ID and Application Secret into Gemini.

The OAuth flow reaches Google’s MCP connection screen, but after continuing it returns:

`Internal Server Error`

Can Google Gemini Spark please be added to the Square MCP client allowlist, or can you confirm whether any additional OAuth configuration is required?

Thank you.

---

<div class="post-metadata">

**Author:** ![zacstlouis](https://avatars.discourse-cdn.com/v4/letter/z/b5a626/32.png) [@zacstlouis](https://developer.squareup.com/forums/u/zacstlouis)\
**Post date:** [September 22, 2026, 3:22pm UTC](https://developer.squareup.com/forums/t/mcp-allowlist-request-google-gemini-spark/27902/3 "2026-09-22T15:22:45Z")

</div>

I have added the oauth callback. It may take up to 5 business days to take effect.