One binary, three faces over one engine — a web UI, a terminal UI and scriptable CLI verbs that work against any MCP server, and come pre-wired when you run one against a gateway.

The four questions an inspector answers — why a tool is missing, why a call was refused, whether the server is conformant, and what the wire actually said — and which surface answers each.

Find out why a server refused you, walk the OAuth discovery chain including the step that failed, get a token with a browser sign-in or with an ID-JAG from your enterprise IdP, bind it to a DPoP key, or present an AAuth agent identity.

List a server's event types, poll one, hold a stream open, or point a webhook subscription at the inspector itself, with every delivery checked against what the extension requires.

Capture an exchange as a single file, replay it anywhere a target goes with the server gone, and attach a reproduction to a bug report without also attaching your gateway.

Exit codes are a contract, so a pipeline can fail on capability drift, on a server that accepts what its own schema forbids, or on a gateway that answered without actually serving.

The gateway-supervised sidecar, the standalone bind and token posture, and the hosted profile — what each guarantees, and what each deliberately refuses.