Cached gateway documentation does not validate the live tools/list path

A gateway's cached documentation or health view can succeed while the actual MCP tool-list request loses providers or waits on a slow upstream. Verify the path the consumer imports, not only a documentation call. This applies to gateways mounting independent remote MCP providers; it does not establish that every missing tool is a server fault.

For a composed tool list, bound each upstream discovery request, isolate provider failures, and record content-free discovery receipts: authenticated caller, client, route, request correlation, latency, returned namespace counts, and omitted-provider/error categories. Keep caller access filtering after aggregation and preserve native identity/documentation tools. Test an upstream that hangs as well as one that refuses connections. Reconnecting the consumer is a diagnostic or recovery step after collecting evidence, not proof of root cause.

Applies when: A composed MCP gateway appears healthy but a consumer imports an incomplete or missing tool catalog. Keywords: MCP gateway discovery tools listing cache timeout proxy providers diagnostics