diff --git a/test/e2e/live/mcp-bridge-tool-discovery.ts b/test/e2e/live/mcp-bridge-tool-discovery.ts
index e6902947bd5..f0e2db0b76e 100644
--- a/test/e2e/live/mcp-bridge-tool-discovery.ts
+++ b/test/e2e/live/mcp-bridge-tool-discovery.ts
@@ -3,6 +3,7 @@
 
 import { expect } from "vitest";
 
+import type { ArtifactSink } from "../fixtures/artifacts.ts";
 import { buildAvailabilityProbeEnv } from "../fixtures/availability-env.ts";
 import { assertExitZero } from "../fixtures/clients/command.ts";
 import type { HostCliClient } from "../fixtures/clients/host.ts";
@@ -39,8 +40,26 @@ export function shouldRetryMcpDiscoveryAfterRestart(
 }
 
 type McpToolDiscoveryStatusJson = {
-  provider: { credentialResolution?: unknown };
-  toolDiscovery: {
+  provider: Record<string, unknown> & {
+    registryPresent: boolean;
+    gatewayPresent: boolean | null;
+    attached: boolean | null;
+    credentialReady: boolean | null;
+    credentialResolution?: unknown;
+  };
+  policy: Record<string, unknown> & {
+    registryPresent: boolean;
+    gatewayPresent: boolean | null;
+  };
+  adapter: Record<string, unknown> & {
+    registered: boolean | null;
+    detail?: unknown;
+  };
+  trustedPrivateTarget?: Record<string, unknown> & {
+    state: "match" | "drift" | "unresolved";
+    detail?: unknown;
+  };
+  toolDiscovery: Record<string, unknown> & {
     ok: boolean;
     count: number;
     tools: string[];
@@ -49,6 +68,56 @@ type McpToolDiscoveryStatusJson = {
   };
 };
 
+function buildMcpToolDiscoveryDiagnostics(
+  status: McpToolDiscoveryStatusJson,
+  requests: readonly FakeMcpRequest[],
+  expectedSecret: string,
+): Record<string, unknown> {
+  return {
+    provider: {
+      registryPresent: status.provider.registryPresent,
+      gatewayPresent: status.provider.gatewayPresent,
+      attached: status.provider.attached,
+      credentialReady: status.provider.credentialReady,
+      credentialResolutionPresent: status.provider.credentialResolution !== undefined,
+    },
+    policy: {
+      registryPresent: status.policy.registryPresent,
+      gatewayPresent: status.policy.gatewayPresent,
+    },
+    adapter: {
+      registered: status.adapter.registered,
+      detailPresent: status.adapter.detail !== undefined,
+    },
+    trustedPrivateTarget: status.trustedPrivateTarget
+      ? {
+          state: status.trustedPrivateTarget.state,
+          detailPresent: status.trustedPrivateTarget.detail !== undefined,
+        }
+      : null,
+    toolDiscovery: {
+      ok: status.toolDiscovery.ok,
+      count: status.toolDiscovery.count,
+      tools: [...status.toolDiscovery.tools],
+      truncated: status.toolDiscovery.truncated,
+      ...(status.toolDiscovery.detail !== undefined ? { detail: status.toolDiscovery.detail } : {}),
+    },
+    requests: requests.map((request) => ({
+      httpMethod: request.method,
+      rpcMethod: request.rpcMethod ?? null,
+      responseStatus: request.responseStatus ?? null,
+      responseHasResult: request.responseHasResult ?? null,
+      sessionMetadataPresent: {
+        sessionId: Boolean(request.sessionId),
+        protocolVersion: Boolean(request.protocolVersion),
+        negotiatedSessionId: Boolean(request.negotiatedSessionId),
+        negotiatedProtocolVersion: Boolean(request.negotiatedProtocolVersion),
+      },
+      credentialRewriteMatched: request.auth === `Bearer ${expectedSecret}`,
+    })),
+  };
+}
+
 export async function assertAuthenticatedMcpRediscovery(
   target: AuthenticatedMcpDiscoveryTarget | undefined,
   requestOffset: number | undefined,
@@ -174,6 +243,7 @@ export async function assertAuthenticatedMcpToolDiscovery(
   host: HostCliClient,
   fakeMcp: FakeMcpHttpsServer,
   options: {
+    artifacts: Pick<ArtifactSink, "writeJson">;
     sandboxName: string;
     artifactPrefix: string;
     credentialKey?: string;
@@ -202,7 +272,6 @@ export async function assertAuthenticatedMcpToolDiscovery(
     );
     assertExitZero(status, `${options.artifactPrefix} mcp status --tools --json`);
     statusJson = JSON.parse(status.stdout) as McpToolDiscoveryStatusJson;
-    expect(statusJson.provider.credentialResolution).toBeUndefined();
     if (
       !shouldRetryMcpToolDiscoveryTransportFailure(
         statusJson.toolDiscovery,
@@ -218,6 +287,12 @@ export async function assertAuthenticatedMcpToolDiscovery(
     await new Promise((resolve) => setTimeout(resolve, MCP_TOOL_DISCOVERY_RETRY_DELAY_MS));
   }
   if (!status || !statusJson) throw new Error("MCP tool discovery did not run");
+  const discoveryRequests = fakeMcp.requests.slice(requestOffset);
+  await options.artifacts.writeJson(
+    `${options.artifactPrefix}-mcp-tool-discovery-diagnostics.json`,
+    buildMcpToolDiscoveryDiagnostics(statusJson, discoveryRequests, options.hostSecret),
+  );
+  expect(statusJson.provider.credentialResolution).toBeUndefined();
   expect(statusJson.toolDiscovery).toMatchObject({
     ok: true,
     count: 2,
@@ -225,7 +300,6 @@ export async function assertAuthenticatedMcpToolDiscovery(
     truncated: false,
   });
   expect(status.stdout).not.toContain(options.hostSecret);
-  const discoveryRequests = fakeMcp.requests.slice(requestOffset);
   const discoveryProtocolRequests = discoveryRequests.filter(
     (request) =>
       (request.method === "POST" || request.method === "DELETE") && request.path === "/mcp",
diff --git a/test/e2e/live/mcp-bridge-trusted-private.ts b/test/e2e/live/mcp-bridge-trusted-private.ts
index 15787880593..9f248992a09 100644
--- a/test/e2e/live/mcp-bridge-trusted-private.ts
+++ b/test/e2e/live/mcp-bridge-trusted-private.ts
@@ -1,6 +1,7 @@
 // SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 // SPDX-License-Identifier: Apache-2.0
 
+import type { ArtifactSink } from "../fixtures/artifacts.ts";
 import { buildAvailabilityProbeEnv } from "../fixtures/availability-env.ts";
 import type { CleanupRegistry } from "../fixtures/cleanup.ts";
 import { assertExitZero as expectExitZero } from "../fixtures/clients/command.ts";
@@ -36,6 +37,7 @@ export async function assertTrustedPrivateMcpRebindingDenied(
   cleanup: CleanupRegistry,
   options: {
     adapter: McpDnsRebindingAdapter;
+    artifacts: Pick<ArtifactSink, "writeJson">;
     artifactPrefix: string;
     assertSecretAbsent: (
       sandbox: SandboxClient,
@@ -164,6 +166,7 @@ export async function assertTrustedPrivateMcpRebindingDenied(
     `${options.artifactPrefix}-dns-rebinding-secret-absent-from-sandbox`,
   );
   await assertAuthenticatedMcpToolDiscovery(host, rebindMcp, {
+    artifacts: options.artifacts,
     sandboxName: options.sandboxName,
     artifactPrefix: `${options.artifactPrefix}-trusted-private`,
     credentialKey: REBIND_CREDENTIAL_KEY,
diff --git a/test/e2e/live/mcp-bridge.test.ts b/test/e2e/live/mcp-bridge.test.ts
index 87afa2d0b30..ae4cb88c542 100644
--- a/test/e2e/live/mcp-bridge.test.ts
+++ b/test/e2e/live/mcp-bridge.test.ts
@@ -779,6 +779,7 @@ test("mcp-bridge", {
     artifactPrefix: "openclaw",
   });
   await assertAuthenticatedMcpToolDiscovery(host, fakeMcp, {
+    artifacts,
     sandboxName: OPENCLAW_SANDBOX_NAME,
     artifactPrefix: "openclaw",
     hostSecret: HOST_SECRET,
@@ -848,6 +849,7 @@ test("mcp-bridge", {
 
   await assertTrustedPrivateMcpRebindingDenied(host, sandbox, cleanup, {
     adapter: "mcporter",
+    artifacts,
     artifactPrefix: "openclaw",
     assertSecretAbsent: assertSecretAbsentFromSandbox,
     cleanupBridge: cleanupMcpBridge,
@@ -1096,6 +1098,7 @@ mcpBridgeShardTest("hermes")(
       },
     });
     await assertAuthenticatedMcpToolDiscovery(host, fakeMcp, {
+      artifacts,
       sandboxName: HERMES_SANDBOX_NAME,
       artifactPrefix: "hermes",
       hostSecret: HOST_SECRET,
@@ -1134,6 +1137,7 @@ mcpBridgeShardTest("hermes")(
     };
     await assertTrustedPrivateMcpRebindingDenied(host, sandbox, cleanup, {
       adapter: "hermes-config",
+      artifacts,
       artifactPrefix: "hermes",
       assertSecretAbsent: assertSecretAbsentFromSandbox,
       cleanupBridge: cleanupMcpBridge,
@@ -1321,6 +1325,7 @@ mcpBridgeShardTest("deepagents")(
       artifactPrefix: "deepagents",
     });
     await assertAuthenticatedMcpToolDiscovery(host, fakeMcp, {
+      artifacts,
       sandboxName: DEEPAGENTS_SANDBOX_NAME,
       artifactPrefix: "deepagents",
       hostSecret: HOST_SECRET,
@@ -1336,6 +1341,7 @@ mcpBridgeShardTest("deepagents")(
     await assertSecretAbsentFromSandbox(sandbox, DEEPAGENTS_SANDBOX_NAME, ["/sandbox/.deepagents"]);
     await assertTrustedPrivateMcpRebindingDenied(host, sandbox, cleanup, {
       adapter: "deepagents-config",
+      artifacts,
       artifactPrefix: "deepagents",
       assertSecretAbsent: assertSecretAbsentFromSandbox,
       cleanupBridge: cleanupMcpBridge,
diff --git a/test/e2e/support/mcp-bridge-tool-discovery.test.ts b/test/e2e/support/mcp-bridge-tool-discovery.test.ts
index 45818a6eebc..72d328dd6de 100644
--- a/test/e2e/support/mcp-bridge-tool-discovery.test.ts
+++ b/test/e2e/support/mcp-bridge-tool-discovery.test.ts
@@ -1,7 +1,12 @@
 // SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 // SPDX-License-Identifier: Apache-2.0
 
+import fs from "node:fs/promises";
+import os from "node:os";
+import path from "node:path";
+
 import { afterEach, describe, expect, it, vi } from "vitest";
+import { ArtifactSink } from "../fixtures/artifacts.ts";
 import { shouldRetryMcpMutationAfterConcurrencyConflict } from "../live/mcp-bridge-cleanup.ts";
 import {
   type FakeMcpHttpsServer,
@@ -12,6 +17,7 @@ import {
 } from "../live/mcp-bridge-servers.ts";
 import {
   assertAuthenticatedMcpDiscoveryWithOneRestart,
+  assertAuthenticatedMcpToolDiscovery,
   hasSuccessfulAuthenticatedMcpDiscovery,
   shouldRetryMcpDiscoveryAfterRestart,
   shouldRetryMcpToolDiscoveryTransportFailure,
@@ -21,6 +27,7 @@ const EXPECTED_SECRET = "expected-secret";
 const EXPECTED_RESULT_TOKEN = "expected-result";
 const SESSION_ID = "fake-session-1";
 const PROTOCOL_VERSION = "2025-03-26";
+const STATUS_SECRET = "unregistered-sensitive-status-value";
 
 function request(rpcMethod: string, overrides: Partial<FakeMcpRequest> = {}): FakeMcpRequest {
   return {
@@ -68,10 +75,14 @@ const BRIDGE_TOOLS = ["tool_search", "tool_describe", "tool_call"].map((name) =>
 }));
 
 let compatibleMock: StartedHttpServer | undefined;
+const artifactRoots: string[] = [];
 
 afterEach(async () => {
   await compatibleMock?.close();
   compatibleMock = undefined;
+  await Promise.all(
+    artifactRoots.splice(0).map((root) => fs.rm(root, { recursive: true, force: true })),
+  );
 });
 
 async function startDeferredCompatibleMock(): Promise<StartedHttpServer> {
@@ -185,6 +196,99 @@ describe("authenticated MCP rediscovery evidence", () => {
 });
 
 describe("authenticated MCP tool discovery transport retry", () => {
+  it("writes redacted boundary diagnostics before a discovery failure (#8746)", async () => {
+    const statusJson = {
+      provider: {
+        registryPresent: true,
+        gatewayPresent: true,
+        attached: true,
+        credentialReady: true,
+        credentialResolution: { detail: STATUS_SECRET },
+        token: STATUS_SECRET,
+      },
+      policy: { registryPresent: true, gatewayPresent: true, token: STATUS_SECRET },
+      adapter: { registered: true, detail: STATUS_SECRET, sessionId: STATUS_SECRET },
+      trustedPrivateTarget: {
+        state: "match" as const,
+        host: STATUS_SECRET,
+        recordedPins: [STATUS_SECRET],
+        detail: STATUS_SECRET,
+      },
+      toolDiscovery: {
+        ok: false,
+        count: 0,
+        tools: [],
+        truncated: false,
+        detail: "MCP tool discovery request failed",
+        credential: STATUS_SECRET,
+      },
+    };
+    const fakeMcp = { requests: [] } as unknown as FakeMcpHttpsServer;
+    const host = {
+      nemoclaw: vi.fn(async () => {
+        fakeMcp.requests.push(successfulInitialize());
+        return { exitCode: 0, stdout: JSON.stringify(statusJson), stderr: "" };
+      }),
+    } as unknown as Parameters<typeof assertAuthenticatedMcpToolDiscovery>[0];
+    const artifactRoot = await fs.mkdtemp(path.join(os.tmpdir(), "nemoclaw-mcp-diagnostics-"));
+    artifactRoots.push(artifactRoot);
+    const artifacts = new ArtifactSink(artifactRoot);
+
+    await expect(
+      assertAuthenticatedMcpToolDiscovery(host, fakeMcp, {
+        artifacts,
+        sandboxName: "sandbox",
+        artifactPrefix: "openclaw-trusted-private",
+        hostSecret: EXPECTED_SECRET,
+        progress: { event: vi.fn() },
+      }),
+    ).rejects.toThrow();
+
+    const artifactPath = path.join(
+      artifactRoot,
+      "openclaw-trusted-private-mcp-tool-discovery-diagnostics.json",
+    );
+    const diagnostics = await fs.readFile(artifactPath, "utf8");
+    expect(JSON.parse(diagnostics)).toEqual({
+      provider: {
+        registryPresent: true,
+        gatewayPresent: true,
+        attached: true,
+        credentialReady: true,
+        credentialResolutionPresent: true,
+      },
+      policy: { registryPresent: true, gatewayPresent: true },
+      adapter: { registered: true, detailPresent: true },
+      trustedPrivateTarget: { state: "match", detailPresent: true },
+      toolDiscovery: {
+        ok: false,
+        count: 0,
+        tools: [],
+        truncated: false,
+        detail: "MCP tool discovery request failed",
+      },
+      requests: [
+        {
+          httpMethod: "POST",
+          rpcMethod: "initialize",
+          responseStatus: 200,
+          responseHasResult: true,
+          sessionMetadataPresent: {
+            sessionId: false,
+            protocolVersion: false,
+            negotiatedSessionId: true,
+            negotiatedProtocolVersion: true,
+          },
+          credentialRewriteMatched: true,
+        },
+      ],
+    });
+    expect(diagnostics).not.toContain(STATUS_SECRET);
+    expect(diagnostics).not.toContain(EXPECTED_SECRET);
+    expect(diagnostics).not.toContain(SESSION_ID);
+    expect(diagnostics).not.toContain(PROTOCOL_VERSION);
+  });
+
   it("retries one generic transport failure before any request reaches the fixture", () => {
     expect(
       shouldRetryMcpToolDiscoveryTransportFailure(