{"version":"2.1.281","anchor":"sdk-can-hand-in-process-mcp-server-manifests-to-the-cli-at-i","canonical_anchor":"sdk-can-hand-in-process-mcp-server-manifests-to-the-cli-at-i","heading":"SDK can hand in-process MCP server manifests to the CLI at initialize","tier":"use","area":"SDK","url":"https:\/\/changelogs.core-directive.com\/v\/2.1.281\/e\/sdk-can-hand-in-process-mcp-server-manifests-to-the-cli-at-i","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.281","markdown":"### SDK can hand in-process MCP server manifests to the CLI at initialize\n\nThe Agent SDK can now read tool lists from in-process MCP servers itself and pass them to the CLI when it starts\n\n**What**\n\nThe Agent SDK lets programs drive Claude Code from code. MCP servers are add-ons that give Claude extra tools, and some of them run inside your own program (\"in-process\"). The SDK's `Query` class has a new step, `captureSdkMcpServerManifests()`.\n\nThis step runs on the first `initialize` when `captureSdkMcpManifests` is set and SDK MCP servers exist. It asks each in-process server to start (`initialize`) and to list its tools (`tools\/list`), all within a time limit. It then sends the results to the CLI inside the `initialize` request, in a new field `sdkMcpServerManifests`. That field sits next to `sdkMcpServers` and `sdkMcpServerConfigs`.\n\nServers that are not captured before the time limit fall back to the older handshake over the control channel, which is a back-and-forth exchange of messages. The result is logged to telemetry (usage data sent back) as `sdk_mcp_manifest_capture`, with one of these outcomes:\n\n- `closed`\n\n- `deadline`\n\n- `partial`\n\n- `success`\n\n**Why**\n\nThe CLI can learn what tools your in-process servers offer without a separate exchange for each one. The capture is controlled by `captureSdkMcpManifests`, which depends on the environment variable `CLAUDE_AGENT_SDK_DISABLE_MCP_MANIFESTS`. Setting that variable turns the capture off.\n\n- Area: SDK\n- Tier: Use it now\n- Useful: 4\/5\n- Signal: 3\/5"}