sandbox_say

Posts a status line to the person watching the box in the app; it is not a way to ask them anything. Their notes come back as fromHuman.

Posts a line to the person watching the box in the app: what you are doing, a change of plan, what you are stuck on. It is a status line, not a way to ask: when you need the person to decide something, ask them in the conversation you are working in, the way your client asks (Claude Code, Codex and the others each have their own), and they answer you there. Notes the person leaves for you in the app are returned once, as fromHuman (a list of messages), in the result of your next tool call on that box, sandbox_status included, and only to the conversation that holds the box (see Picking up a box another conversation left): another conversation looking at the box does not take them. Images they attach follow the JSON as image content, in the same order; the message says how many.

Every tool and topic is listed in the tool reference.