Claude Code v2.1.221 ·
Connected client record exposes protocol details and goes through an adoption hook
Connected MCP servers now track their negotiated protocol, and a failed wiring step no longer breaks the connection.
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
Internal ChangesKind: in v2.1.221,
Internal ChangesSection of the release
What
The object returned for a connected MCP server carries protocol metadata and is handed to a registered wiring callback.
Details
- The record now includes
negotiatedProtocolVersion and protocolEra alongside capabilities and instructions. - After building it, the connect path calls a registered wiring callback.
- If that callback throws, the connection still succeeds and a warning is logged saying the placeholder is retained and adoption will retry.
Evidence
connected-client wiring failed (placeholder retained, adoption will retry)
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
See this entry in the whole of v2.1.221 →
