You'll noticeTier: how much it should matter to you
2Useful: my rating, 1 to 5
1Signal: worth watching, 1 to 5
MCPArea: what it touches
ImprovementsKind: in v2.1.273,
ImprovementsSection of the release
What
When an MCP (Model Context Protocol, used to connect Claude Code to external tool servers) tool call fails because of invalid or expired credentials, the error message now distinguishes four situations instead of two:
A claude.ai connection needs to be reconnected
A credential was rejected by the server's headersHelper (with guidance to check the helper and run /mcp to reconnect or authenticate)
A statically configured Authorization header was rejected
A generic prompt to re-authenticate
Why
More specific error messages help you fix the actual problem, for example checking a custom headersHelper versus simply running /mcp to reconnect, rather than getting the same vague re-authorization prompt regardless of cause.
How sure we are
One source agreesOne thing we can check says the same as this entry.
Anthropic's release notes agreeAdded a notification when an MCP server disconnects mid-session and automatic reconnection gives up, pointing at /mcp
