The credentialed engineer or geoscientist who takes personal responsibility for technical disclosure under NI 43-101.
Under NI 43-101, a qualified person is an engineer or geoscientist with at least five years of relevant experience in mineral exploration, mine development, or operations. QPs are responsible for preparing and approving technical reports and resource estimates.
The QP requirement is the accountability mechanism of the whole standard. Someone with a professional designation and a reputation to lose has to sign off, which is why compliant estimates carry weight that a company's own claims do not.
Look for who the QP is and whether they are independent of the company. An independent QP on a resource estimate is a meaningfully stronger signal than an internal one.