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 v2.1.290,
ImprovementsSection of the release
What
MCP servers are outside programs that give Claude Code extra tools. Some connect over HTTP or through the claude.ai proxy. If one of those connections closes after the server has already received a tool call, Claude Code now fails the call instead of sending it again. It logs that the call was "not sent again: the connection closed after the server took the call".
Why
Some tools do something each time they run, such as creating a record or sending a message. Sending the call twice could make that happen twice.
