Under the hoodTier: how much it should matter to you
2Useful: 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
Connected MCP client records now carry a protocol era and the negotiated protocol version, derived from a server/discover-based negotiation, and that era decides which permission channel is used.
Details
New fields protocolEra and negotiatedProtocolVersion on connected client records.
Connection telemetry emits both alongside negotiationMode.
The experimental claude/channel/permission path is now used only for servers whose era is not modern (r.protocolEra !== "modern").
Tool-schema compatibility checks take the era as an argument.
Evidence
protocolEra
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
