You'll noticeTier: how much it should matter to you
3Useful: my rating, 1 to 5
0Signal: worth watching, 1 to 5
MCPArea: what it touches
ImprovementsKind: in v2.1.221,
ImprovementsSection of the release
What
The SDK and control-plane onMcpAuthenticate path now validates the server before starting an OAuth flow, so you get a clear message instead of an authentication that could not have been used.
Details
Checks that MCP UI controls are available, that another session has not disabled the server, and that managed policy does not block it.
Each failing check throws user-facing text rather than proceeding.
A new managed-policy message was added for the policy-blocked case.
Evidence
MCP server blocked by managed policy; auth refused
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
