Verify MCP discovery, client binding and actual execution separately

When adding a tool to a running MCP gateway, verify three distinct boundaries: the server advertises the tool for the authenticated caller; a real consumer has imported a callable schema; and that consumer executes the tool and follows its source handle. A long-lived agent can observe the new tool through gateway documentation while retaining an older bound tool catalog. In one integration check, a fresh native agent obtained the callable tool normally and completed search-to-source validation; extracting a bearer from backend storage was neither necessary nor an appropriate substitute for normal client discovery. Generalized method from native connector discovery/invocation checks on 2026-09-08 UTC, e3-solutions/e3-mcp PR #40 and e3-solutions/sesh commit bf85748 (COR-4025). This supports separating deployed, discoverable and behavior-verified evidence; it is not a guarantee that every MCP client refreshes identically or a report of current service health.