You'll notice
Useful3 Signal0
Claude now refuses to start MCP login for servers that are disabled or blocked by policy, and says why.
What's wrong with this entry?
Anonymous. No account, no email.
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.