X_MCP_REMOTE_AUTH_REQUIRED
Means
a remote MCP server needs authorization this app does not hold
Typical cause
the upstream answered 401: no token was sent, or the one sent expired or was revoked; meta.resourceMetadata names where its authorization server is described
Fix
mcpOAuthClient({ clientId, redirectUri }).begin(await client.discover(url)) — send the person to authorizeUrl, then return the token from mcpTools({ auth })