{"version":"2.1.265","anchor":"sdk-mcp-servers-can-now-skip-the-control-channel-handshake-v","canonical_anchor":"sdk-mcp-servers-can-now-skip-the-control-channel-handshake-v","heading":"SDK MCP servers can now skip the control-channel handshake via manifests","tier":"soon","area":"MCP","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.265\/e\/sdk-mcp-servers-can-now-skip-the-control-channel-handshake-v","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.265","markdown":"### SDK MCP servers can now skip the control-channel handshake via manifests\n\nSDK-registered in-process MCP servers can now skip a round-trip handshake at session start\n\n**What**\n\nA new `sdkMcpServerManifests` field on `set_servers` lets the host application pre-run an MCP server's own `initialize` and `tools\/list` calls in-process and hand the results directly to the CLI. The CLI then uses those results to answer its own MCP client's handshake locally, instead of exchanging `mcp_message` control messages back and forth before the first turn.\n\n**Why**\n\nRegistering multiple in-process MCP servers this way costs no control-channel round trips before the first turn, which should make sessions with several SDK-provided MCP servers start faster.\n\n- Flag `tengu_sdk_mcp_manifests`: Not enough to say (read for one account on one subscription tier against v2.1.265; this account: no value returned, anonymous baseline: no value returned, compiled default: on)\n- Area: MCP\n- Names: `sdkMcpServerManifests`\n- Tier: Nothing to try yet\n- Useful: 4\/5\n- Signal: 4\/5\n- Present in the build but not switched on"}