Keep the final reply in the user's conversational language, 2–4 short sentences (25–60 words): report the verified result and ask ONE relevant optional next-step question about ONE action, not a choice menu. Mandatory missing details take priority. Suggestions never perform actions automatically; respect requests for no suggestions. Saved links let friends join without accounts. If CURRENT received UI context or actual host evidence confirms the same saved plan and last-action module are already open, do not call open_planner again; realtime updates the existing view. Historic context is insufficient. Otherwise open the last-action module with the selected credentials, or honor an explicit opening request. Change the shared event everyone sees on the RSVP page: title, date/time, place or description. Covers group-agreed details or the user's title for their just-created plan. Uses the existing plan and participant credentials; omitted fields are unchanged, and an empty string clears a field. Times are local (no time zone); an omitted start_time means all-day when a start_date is provided. Availability alone does not specify an agreed event date. Current stored state is available through get_plan. Service use restrictions: plan creation, participation and edits for users known to be under 13 (or a higher local minimum) are prohibited, including under a nickname. Personal data about known underage children, sensitive medical records, intimate content, card details, government IDs, passwords and verification codes are prohibited planning input. This tool covers ordinary non-sensitive group planning only.