{"version":"2.1.246","anchor":"mcp-calls-made-over-the-control-channel-report-client-cancel","canonical_anchor":"mcp-calls-made-over-the-control-channel-report-client-cancel","heading":"MCP calls made over the control channel report client cancellation","tier":"notice","area":"MCP","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.246\/e\/mcp-calls-made-over-the-control-channel-report-client-cancel","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.246","markdown":"### MCP calls made over the control channel report client cancellation\n\nAn interrupted MCP call over the SDK control channel now returns a real error naming the server.\n\n**What**\n\nWhen a tool call issued through the SDK control channel is interrupted, the handler now returns an error naming the MCP server instead of a normal, empty-looking content response.\n\n**Details**\n\n- The message is built at runtime from the fixed text \"mcp_call cancelled by client: \" followed by the server name.\n- Triggered by an `interrupted` field on the tool result; unconditional for control-channel MCP calls.\n\n**Evidence**\n\n`mcp_call cancelled by client: `\n\n- Area: MCP\n- Tier: You'll notice\n- Useful: 2\/5\n- Signal: 1\/5"}