{"version":"2.1.290","anchor":"mcp-call-is-not-retried-if-the-connection-closes-after-serve","canonical_anchor":"mcp-call-is-not-retried-if-the-connection-closes-after-serve","heading":"MCP tool calls are not re-sent after the server has already received them","tier":"notice","area":"MCP","scope":"individual","heads_up":false,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.290\/e\/mcp-call-is-not-retried-if-the-connection-closes-after-serve","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.290","markdown":"### MCP tool calls are not re-sent after the server has already received them\n\nIf an MCP connection drops after the server took a call, the call now fails instead of being sent again\n\n**What**\n\nMCP 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\".\n\n**Why**\n\nSome 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.\n\n- Area: MCP\n- Tier: You'll notice\n- Useful: 2\/5\n- Signal: 1\/5\n- Scope: individual\n- Heads-up: no"}