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What to ask an MCP vendor, and what “unknown” really means

Public metadata answers provenance, transport and authentication. It almost never answers audit logging, retention, residency or access control at the level of a specific server. Those are the questions worth a vendor's time, and the ones worth putting in writing.

What “unknown” means here#

On this site, unknown means we found no source either way. It is never a synonym for unsupported, and it says nothing about the product.

A vendor may run excellent controls and document none of them publicly. From outside, that is indistinguishable from having none — which is precisely why the questionnaire exists.

So do not treat a column of unknowns as a verdict. Treat it as your agenda.

Questions about the specific server#

Does this MCP server write an audit record when a tool is invoked? What is recorded, and how do we retrieve it?

What does the server retain from a session, and for how long?

In which region does this endpoint process requests? Is that configurable?

Which tools can write or delete? Is there a configuration that disables them?

Can access be scoped per user or per workspace, or is a single credential shared across everyone who connects?

Questions about the company, kept separate#

Which compliance attestations cover *this service* specifically, as opposed to the company's flagship product?

Is there a DPA covering this endpoint, and a sub-processor list that includes it?

How are incidents affecting this endpoint communicated, and is it on your public status page?

Keeping these separate from the server questions matters. A company-level attestation is real evidence about a company and no evidence at all about whether one particular endpoint logs tool calls.

Questions

Should we reject a server because criteria are undocumented?
Not automatically. Undocumented means unanswered, and most vendors will answer directly when asked. What is worth treating as a signal is a vendor who will not answer in writing.

Figures in this guide are computed from the catalog on and update when it does.

Put this into practice

Build a shortlist, apply these criteria, and export an evaluation with every source and date attached. No account needed.