Your organisation blocks a server by policy. You add an allowlist entry for it in your own settings, hoping to readmit it for your team. What happens?

The principle — An allowlist and a denylist are not two sides of one scale. They are two checks that run in a fixed order, and the first one is decisive.

Why the key is correct — Before loading a server, entries from every settings source are merged and the denylist is checked first. A server that matches any denylist entry is blocked, and nothing overrides a denylist match. Adding an allow entry therefore changes nothing, because the evaluation never reaches the allowlist.

Why the others are wrong — Specificity does not enter into it, since the two lists are consulted in sequence rather than compared. Denylists merge from every source regardless, so the block is not confined to the scope that declared it. And an entry in a policy source is not yours to remove from your own file.

Remember this — Deny is checked first and it is final; allow only decides among what survived.

Sources — Anthropic's Claude Code managed MCP guide.