Codex CLI Vercel MCP login fails with “The app redirect URL is invalid”

[tesvm]

I’m unable to authenticate Vercel MCP from Codex CLI. The browser opens Vercel OAuth, but Vercel
stops the flow with:

“The app redirect URL is invalid”

Details:

• MCP server: https://mcp.vercel.com
• client_id: cl_WbdtcToDrMR4ZHvXLGAmbfoYCsQjMeS8
• redirect_uri example: http://127.0.0.1:49683/callback/J69OfRTZqnV5
• Codex CLI: 0.134.0
• observed: May 27, 2026
• OS: macOS

Steps:

1. Run codex mcp add vercel --url https://mcp.vercel.com
2. Browser opens Vercel OAuth
3. Vercel shows “The app redirect URL is invalid”

I also tried:

• codex mcp login vercel
• re-adding the MCP server
• installing via npx add-mcp https://mcp.vercel.com -a codex

Please verify that Codex CLI localhost callback URLs on 127.0.0.1 with dynamic ports are
allowlisted for this Vercel MCP OAuth client.

Docs:

• Use Vercel's MCP server

• Troubleshooting Sign in with Vercel

  

[tesvm]

For reference, the failing command was:

codex mcp add vercel --url https://mcp.vercel.com

The OAuth flow then generated a callback like:

http://127.0.0.1:49683/callback/J69OfRTZqnV5

Vercel rejected it before returning to Codex.

That usually removes one back-and-forth.

[luchao2012 (luchao)]

Has this been resolved? What would be the solution?