You'll noticeTier: how much it should matter to you
2Useful: my rating, 1 to 5
1Signal: worth watching, 1 to 5
AgentsArea: what it touches
ImprovementsKind: in v2.1.314,
ImprovementsSection of the release
What
Apps that drive Claude Code, such as those built on the Agent SDK, use mcp_authenticate to sign in to an MCP server (an outside service that gives Claude extra tools) and claude_authenticate to sign in to Claude itself. Three things changed:
When mcp_authenticate fails a client registration check, the error now carries the code mcp_client_registration_unavailable. Before, these errors had no code.
When the MCP server requires a client registration, Claude Code no longer sends a redirect address.
claude_authenticate has an additional check that can refuse a login.
Why
Apps can now recognise MCP servers that have no client registration available and tell the user why sign-in failed, instead of showing a generic error.
Read from
Names in the bundlemcp_authenticateclaude_authenticate
