Stitch MCP (stitch.googleapis.com) fails with 'Incompatible auth server: does not support dynamic client registration'

[pinki42240]

Description

When using the Stitch MCP server (stitch.googleapis.com/mcp) configured with an API key header, Claude Code throws:

Incompatible auth server: does not support dynamic client registration

Configuration

In ~/.claude.json:

{
  "mcpServers": {
    "stitch": {
      "type": "http",
      "url": "https://stitch.googleapis.com/mcp",
      "headers": {
        "X-Goog-Api-Key": "<api-key>"
      }
    }
  }
}

Expected behavior

Claude Code should use the provided API key header for authentication instead of attempting OAuth dynamic client registration.

Actual behavior

Claude Code ignores the headers config and attempts OAuth discovery, which fails because Google Stitch does not support dynamic client registration.

Steps to reproduce

1. Add the Stitch MCP server to ~/.claude.json with an X-Goog-Api-Key header
2. Try to call any mcp__stitch__* tool
3. Error: Incompatible auth server: does not support dynamic client registration

Environment

• Claude Code version: latest
• OS: macOS

[tangochris]

@pinki42240 I had the same issue. Upgrading to latest Claude Code solved it.

[Nikolai-Cook]

I'm on v2.1.92 and still getting the same issue

[bbensky]

Still broken on Claude Code 2.1.132 (and 2.1.140 has the same code path).

Config is type: http with an Authorization: Bearer <ADC token> header for the GCP MCP endpoints (gke, cloud-monitoring, etc). claude mcp list shows them all Connected, tool schemas load — but tools/call dies with the DCR error.

Curl with the same Bearer works end-to-end (initialize, tools/list, tools/call all 200). Google's *.googleapis.com/mcp endpoints 404 on /.well-known/oauth-authorization-server, so the server never advertised OAuth. Claude Code is initiating DCR on its own when invoking a tool.

No env var to disable it that I could find. Working around by shelling out to gcloud/kubectl.