Supabase MCP authentication not triggering in Claude Code (Cursor)

[Williamlabussiere]

Hi,

I'm trying to set up Supabase MCP with the Claude Code extension in Cursor IDE but the automatic authentication flow isn't working. What I've done:

1/ Added this to .claude.json:
{
"mcpServers": {
"supabase": {
"type": "http",
"url": "https://mcp.supabase.com/mcp"
}
}
}

not working

2/ Created .mcp.json in project root with:
{
"mcpServers": {
"supabase": {
"transport": {
"type": "sse",
"url": "https://mcp.supabase.com/mcp"
}
}
}
}

not working

3/ Restarted Cursor/VSCode multiple times
4/ Tried both with and without explicit transport type

Expected: Browser window opens for Supabase authentication
Actual: No authentication prompt appears, no MCP connection established
Workaround attempted: Created a personal access token and added it via Authorization: Bearer header in the config, but still no connection.

Environment:
IDE: Cursor with Claude Code extension
OS: macOS
No errors in Claude Code output logs (completely blank)

Is there a specific setup step for Claude Code in Cursor, or a way to manually trigger the authentication flow?

[raqibhayder]

@Williamlabussiere: getting the same error. Were you able to resolve it?

[Williamlabussiere]

@raqibhayder no, still cant use supabase mcp with claude code extension for the moment unfortunately

[trelea2aidk]

Im getting same issues.

[Williamlabussiere]

It's working for me now.

I had to go directly in claude code via my terminal (not using claude code via VSCode or Cursor extension): https://docs.claude.com/en/docs/claude-code/overview

Then when typing this command line I was properly redirected to supabase to authenticate : claude mcp add --transport http supabase "https://mcp.supabase.com/mcp".

After that when you type /mcp in claude code you should see supabase mcp active. And from there, it will work in claude code extension in VSCode or Cursor.

@raqibhayder @trelea2aidk

[trelea2aidk]

thanks, just fixed /mcp

[fakossa-c]

Thanks 🙏🙏🙏

[a3894281]

This is working for me.
Thanks.

[eugenesaz]

I tried the mentioned steps but still getting Error: Dynamic client registration failed: HTTP 404

any ideas?

[Umair-Syed]

For me it worked after I reset Claude config (I had mistakenly made .claude.json invalid; claude reset it for me.) then I added supabase mcp in the terminal and open claude code in terminal, on /mcp, Supbase mcp was still unauthenicated but it allowed me to login and redirected to browser for auth.

[aantti]

Cc @mattrossman @gregnr

[mattrossman]

Hey folks, we've updated the docs to call out the claude /mcp step for triggering authentication in Claude Code.

[edam016]

Encountered the same issue, what worked for me was using the PAT in my mcp.json

[a3894281]

Still, not working with claude code.

[adamosean]

For those still facing authentication issues, here is the recommended fix by manually updating your .mcp.json file.

Generate your Personal Access Token

• You must first create a new token here: Supabase Access Tokens
• Update your .mcp.json

Insert the following configuration, replacing YOUR BEARER TOKEN, <your_project_scope>, and the feature list.

Note on URL Parameters:

• project_ref: This is the unique identifier found in your Supabase project URL, between https:// and .supabase.co. (e.g., https://**xxxxxxxxxx**.supabase.co $\rightarrow$ xxxxxxxxxx).
• features: The required capabilities (e.g., docs, database, debug, functions) can be configured/retrieved directly from the Supabase Dashboard. Navigate to your project, click the Connect button, and go to the MCP tab in the modal.

"supabase": {
      "type": "http",
      "url": "[https://mcp.supabase.com/mcp?project_ref=](https://mcp.supabase.com/mcp?project_ref=)<your_project_scope>&features=<all_capabilities_that_you_want_to_give_access>",
      "headers": {
        "Authorization": "Bearer YOUR BEARER TOKEN"
      }
    }

Official Reference:

• For more context, check the Manual Authentication section of the official documentation (thanks, @mattrossman !): Supabase Docs: Manual MCP Authentication

[CarnivorMusic]

I spent a few hours trying to connect Supabase MCP with Cursor and for some reason the integration was giving me nothing but issues. I tried different configurations trying to add the MCP server but the redirect url for OAuth was not working at all it wasn’t reaching the auth callback during connection which made the connection fail 100% of the time. So after deep research and many failures I figured out a fail proof method to connect Supabase MCP to Cursor if you’re struggling like me.

###The Workaround That Works

1. Save your MCP configuration in Cursor (the standard Supabase MCP setup)
2. Attempt to connect Supabase — it will fail with “Unauthorized” (settings > Tools & MCP)
3. Check the Cursor logs (Output panel) to find the authorization URL that starts with https://api.supabase.com/v1/oauth/authorize?...
4. Manually copy and paste that URL into your browser
5. Complete the OAuth authorization in the browser
6. The callback successfully returns to Cursor and establishes the connection

This works as long as you have your project ref and personal access token.