MCP OAuth Connect

Free checker for when an MCP remote answers curl but dies in Claude / Cursor / Desktop / Grok Connectors.

Live checker	check.gfbytes.com
This repo	CLI diagnose.py + plugin / skill
Web UI	mcp-gfbytes
Demo MCP	https://mcp.gfbytes.com

Part of GFB's lab surface. Founder / peer identity: gregfredabytes.com · essay · what I run

What this is not

• Not a hosted MCP product. https://mcp.gfbytes.com is a ping-only reference server.
• Not a completed handshake. The checker reads discovery metadata. It does not do DCR, mint a token, or call tools/list. A fail is a scoping signal, not a dead end.
• Not the paid attach lab. Four-client attempt + written path lives on the studio product page.

Paste only the URL in a Connectors UI — no API key.

Clone / run

Stdlib Python ≥3.10. No install for the checker:

git clone https://github.com/GFB2026/mcp-oauth-connect.git
cd mcp-oauth-connect
python skills/mcp-oauth-connect/scripts/diagnose.py https://mcp.gfbytes.com

Exit 0 if connector-critical checks pass; 1 otherwise. JSON report on stdout.

Looks for a proper login challenge (not a bare 200 from curl), a registration endpoint, PKCE S256, and RFC 9728 protected-resource metadata.

Tests:

python -m pip install "pytest>=8"
python -m pytest

For AI assistants / contributors

Edit lanes and hard stops: .github/copilot-instructions.md. Verify with python -m pytest (install pytest>=8; this tree is flat — no pip install -e).

Plugin install (optional)

Claude Code:

/plugin marketplace add GFB2026/mcp-oauth-connect
/plugin install mcp-oauth-connect@mcp-oauth-connect

Grok Build:

grok plugin marketplace add GFB2026/mcp-oauth-connect
grok plugin install mcp-oauth-connect --trust

Then run the same diagnose.py path as above.

template/

Public ping-only example behind https://mcp.gfbytes.com (MIT). Reference server, not a service SKU.

License

MIT for the plugin, skill, diagnose script, tests, and template/. Studio attach-lab / fix-round services are separate offers on gfbytes.com.