Most failures are one of four things: the client never started OAuth, the account is not admin, the cache is empty, or you called the wrong skill.
The client never opens a login window
The first request to /mcp without a session is 401. That is how the client is supposed to find OAuth. If nothing opens, the client may expect a static header. Remove extra Authorization keys and try Cursor or Grok with only:
{
"mcpServers": {
"linkdr": {
"url": "https://linkdr.com/mcp"
}
}
}See Auth and Connect MCP.
I signed in and still get 403
Login worked. The user is not an admin. Research tools refuse non-admins. Checkout with SKILL.md still works for that account.
Consent shows a long id
The client did not send a display name. The page says "MCP client". You can still Allow. That is not a failed login.
miss or no_snapshot
We do not have that domain or a usable SERP. Skip it, try another keyword, or tell the user. Do not treat either status as live Google.
429
You made more than 120 research calls in an hour. Wait until the window resets. Ask for fewer keywords next time.
The agent quoted placement prices from MCP
It used research tools as a price list. They are not. Ordering is managed backlinks. Research is keywords, creators, and emails.
The agent walked /onboarding
Point it at https://linkdr.com/SKILL.md again. The skill is explicit: one checkout URL, no wizard.