Try changes on a throwaway copy of a database before making them for real.
action=start makes an in-memory copy of the database. From then on EVERY call in this session on that database - reads and writes - goes to the copy, and each result begins 'TRIAL COPY of ...'. Nothing on the copy is ever saved.
Check the outcome (query_aql, describe_set, get_report_data ...). Then action=discard to throw the copy away and return to the real database. To keep the changes, make the same calls again after discarding - there is no commit.
action=status lists this session's trials.
While any trial is on, tools whose effects would reach beyond the copy are refused: imports, create/delete database, delete report/import template, library copies, upload links, and the name history tools.
Use it for a risky restructure, a bulk edit:, or a first attempt at an unfamiliar write. A copy holds the whole database in server memory - start warns when the database is large - so discard it as soon as you are done. A copy unused for 2 hours is discarded by the server; calls then fail loudly until you discard the trial here.
A trial belongs to this MCP session only; another agent on the same key keeps working on the real database.
