Some programs drive Claude Code from the outside, for example a remote client or an editor that attaches to a running session. When such a program connects, it sends an initialize request and Claude Code replies. That reply can now carry an optional list of pending elicitation requests.
An elicitation request is a question that an MCP server asks you partway through a task. An MCP server is an outside program that gives Claude Code extra tools. The new list holds every such question Claude Code has passed on that nobody has answered yet and that has not been withdrawn.
The field is optional. Not every session fills it in yet, so a connecting program cannot count on finding it.
A client that attaches after a question was asked can still show that question and let you answer it. Without the list, the client would miss the question, and the MCP server would be left waiting.