More than it expects. Bank mandates, accountant's records, tax filings, payroll registers, supplier contracts, lease agreements and email approvals all exist even where formal HR documents do not. Corporate registry filings show ownership. Start from what the business genuinely has before commissioning anything new.
Ask the accountant before the printer
External advisers often hold the most reliable contemporaneous record of who ran what: filings, correspondence and signed authorisations. Gather those first. Then identify the few documents worth creating properly from this point onward, such as a written delegation of authority or minuted appointments.
Creating a document today and offering it as evidence of past authority is a different thing, and counsel should decide how anything recent is characterised. Ask the accountant for the file rather than for a summary, since the file contains the contemporaneous correspondence and the summary contains the accountant's recollection. Annual filings, correspondence with lenders, applications for credit facilities and signed engagement letters all record who was acting for the business at a given date, and they were created for purposes that had nothing to do with this.
Where the business decides to formalise a delegation of authority going forward, date it honestly and let counsel decide how it is characterised, because a recent document offered as evidence of past authority creates a new problem rather than solving the old one.