diff --git a/src/agents/openclaw-tools.sessions.test.ts b/src/agents/openclaw-tools.sessions.test.ts
index 9a49d558390..a87fa136225 100644
--- a/src/agents/openclaw-tools.sessions.test.ts
+++ b/src/agents/openclaw-tools.sessions.test.ts
@@ -1,3 +1,5 @@
+import fs from "node:fs";
+import os from "node:os";
 import path from "node:path";
 import { beforeEach, describe, expect, it, vi } from "vitest";
 import type { ChannelMessagingAdapter } from "../channels/plugins/types.js";
@@ -297,9 +299,7 @@ describe("sessions tools", () => {
       params: {
         activeMinutes: undefined,
         agentId: "main",
-        includeDerivedTitles: true,
         includeGlobal: true,
-        includeLastMessage: true,
         includeUnknown: true,
         label: "mailbox",
         limit: undefined,
@@ -356,6 +356,93 @@ describe("sessions tools", () => {
     expect(cronDetails.sessions?.[0]?.kind).toBe("cron");
   });
 
+  it("derives mailbox previews only after agent visibility filtering", async () => {
+    const tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), "openclaw-sessions-list-preview-"));
+    const storePath = path.join(tmpDir, "sessions.json");
+    try {
+      fs.writeFileSync(
+        path.join(tmpDir, "visible.jsonl"),
+        [
+          JSON.stringify({ type: "session", id: "visible" }),
+          JSON.stringify({ message: { role: "user", content: "Visible project kickoff" } }),
+          JSON.stringify({ message: { role: "assistant", content: "Visible latest reply" } }),
+        ].join("\n"),
+        "utf-8",
+      );
+      fs.writeFileSync(
+        path.join(tmpDir, "hidden.jsonl"),
+        [
+          JSON.stringify({ type: "session", id: "hidden" }),
+          JSON.stringify({ message: { role: "user", content: "Hidden cross-agent topic" } }),
+          JSON.stringify({ message: { role: "assistant", content: "Hidden latest reply" } }),
+        ].join("\n"),
+        "utf-8",
+      );
+
+      callGatewayMock.mockImplementation(async (opts: unknown) => {
+        const request = opts as { method?: string; params?: Record<string, unknown> };
+        if (request.method === "sessions.list") {
+          expect(request.params?.includeDerivedTitles).toBeUndefined();
+          expect(request.params?.includeLastMessage).toBeUndefined();
+          return {
+            path: storePath,
+            sessions: [
+              {
+                key: "agent:main:main",
+                kind: "direct",
+                sessionId: "visible",
+                updatedAt: 20,
+              },
+              {
+                key: "agent:other:main",
+                kind: "direct",
+                sessionId: "hidden",
+                updatedAt: 21,
+              },
+            ],
+          };
+        }
+        return {};
+      });
+
+      const tool = createOpenClawTools({
+        agentSessionKey: "agent:main:main",
+        config: {
+          ...TEST_CONFIG,
+          tools: {
+            sessions: { visibility: "agent" },
+            agentToAgent: { enabled: false },
+          },
+        } as OpenClawConfig,
+      }).find((candidate) => candidate.name === "sessions_list");
+      expect(tool).toBeDefined();
+      if (!tool) {
+        throw new Error("missing sessions_list tool");
+      }
+
+      const result = await tool.execute("call-preview", {
+        includeDerivedTitles: true,
+        includeLastMessage: true,
+      });
+      const details = result.details as {
+        sessions?: Array<{
+          key?: string;
+          derivedTitle?: string;
+          lastMessagePreview?: string;
+        }>;
+      };
+      expect(details.sessions).toHaveLength(1);
+      expect(details.sessions?.[0]).toMatchObject({
+        key: "agent:main:main",
+        derivedTitle: "Visible project kickoff",
+        lastMessagePreview: "Visible latest reply",
+      });
+      expect(JSON.stringify(details.sessions)).not.toContain("Hidden");
+    } finally {
+      fs.rmSync(tmpDir, { recursive: true, force: true });
+    }
+  });
+
   it("sessions_list resolves transcriptPath from agent state dir for multi-store listings", async () => {
     callGatewayMock.mockImplementation(async (opts: unknown) => {
       const request = opts as { method?: string };
diff --git a/src/agents/tools/sessions-list-tool.ts b/src/agents/tools/sessions-list-tool.ts
index 91b1b841388..4d6cd130e52 100644
--- a/src/agents/tools/sessions-list-tool.ts
+++ b/src/agents/tools/sessions-list-tool.ts
@@ -8,6 +8,8 @@ import {
 } from "../../config/sessions.js";
 import type { OpenClawConfig } from "../../config/types.openclaw.js";
 import { callGateway } from "../../gateway/call.js";
+import { readSessionTitleFieldsFromTranscript } from "../../gateway/session-utils.fs.js";
+import { deriveSessionTitle } from "../../gateway/session-utils.js";
 import { resolveAgentIdFromSessionKey } from "../../routing/session-key.js";
 import { normalizeOptionalLowercaseString, readStringValue } from "../../shared/string-coerce.js";
 import {
@@ -105,8 +107,8 @@ export function createSessionsListTool(opts?: {
       const label = readStringParam(params, "label");
       const agentId = readStringParam(params, "agentId");
       const search = readStringParam(params, "search");
-      const includeDerivedTitles = params.includeDerivedTitles === true ? true : undefined;
-      const includeLastMessage = params.includeLastMessage === true ? true : undefined;
+      const includeDerivedTitles = params.includeDerivedTitles === true;
+      const includeLastMessage = params.includeLastMessage === true;
       const gatewayCall = opts?.callGateway ?? callGateway;
 
       const list = await gatewayCall<{ sessions: Array<SessionListRow>; path: string }>({
@@ -117,8 +119,6 @@ export function createSessionsListTool(opts?: {
           label,
           agentId,
           search,
-          includeDerivedTitles,
-          includeLastMessage,
           includeGlobal: !restrictToSpawned,
           includeUnknown: !restrictToSpawned,
           spawnedBy: restrictToSpawned ? effectiveRequesterKey : undefined,
@@ -309,6 +309,32 @@ export function createSessionsListTool(opts?: {
           lastAccountId,
           transcriptPath,
         };
+        if (sessionId && (includeDerivedTitles || includeLastMessage)) {
+          const fields = readSessionTitleFieldsFromTranscript(
+            sessionId,
+            storePath,
+            sessionFile,
+            resolvedAgentId,
+          );
+          if (includeDerivedTitles && !row.derivedTitle) {
+            const derivedTitle = deriveSessionTitle(
+              {
+                sessionId,
+                displayName: row.displayName,
+                label: row.label,
+                subject: readStringValue((entry as { subject?: unknown }).subject),
+                updatedAt: typeof row.updatedAt === "number" ? row.updatedAt : 0,
+              },
+              fields.firstUserMessage,
+            );
+            if (derivedTitle) {
+              row.derivedTitle = derivedTitle;
+            }
+          }
+          if (includeLastMessage && !row.lastMessagePreview && fields.lastMessagePreview) {
+            row.lastMessagePreview = fields.lastMessagePreview;
+          }
+        }
         if (messageLimit > 0) {
           const resolvedKey = resolveInternalSessionKey({
             key,