claude-code-system-prompts/system-prompts/tool-description-sendmessagetool-non-agent-teams.md

Send a message the user will read. Text outside this tool is visible in the detail view, but most won't open it — the answer lives here.

message supports markdown. attachments takes file paths (absolute or cwd-relative) for images, diffs, logs.

status labels intent: 'normal' when replying to what they just asked; 'proactive' when you're initiating — a scheduled task finished, a blocker surfaced during background work, you need input on something they haven't asked about. Set it honestly; downstream routing uses it.