Sign in to the user's Microsoft To Do account (device-code flow), or report current sign-in status. Call this whenever another To Do tool returns error 'not_signed_in'. Returns a sign-in URL and code to relay to the user; it does not block waiting for them.

List all of the user's Microsoft To Do lists, organized by their group/folder. Use when the user asks what lists they have, or to disambiguate a list name. Also refreshes the group mapping and reports any renamed or deleted lists.

Fetch tasks from a Microsoft To Do list by name, optionally scoped to a group/folder (e.g. 'the Backlog list from Work'). Returns titles, status, due dates, notes and checklist subtasks. Defaults to open (not completed) tasks only.

Create a new task in a Microsoft To Do list, optionally with notes, a due date, importance, and checklist subtasks.

Mark one or more Microsoft To Do tasks as completed. Batch-friendly: pass every finished task id at once. Use the list_id and task ids returned by todo_get_tasks.

Update a Microsoft To Do task: change its title, due date, importance, or status. To reopen a completed task set status to 'notStarted'. To clear the due date pass due_date as null.

Append a timestamped note to a Microsoft To Do task's notes/body WITHOUT erasing existing content. Use to record explanations, decisions, or what was done on a task.

Add, check off, or uncheck checklist subtasks on a Microsoft To Do task. Provide at least one of add / check / uncheck.

Assign Microsoft To Do lists to named groups/folders that mirror how the user organizes them in the To Do app, so lists can later be found by group. Also used to move a list to a different group (set group) or clear it (set group to null). Each assignment's 'list' may be a list name or a listId.