diff --git a/src/agents/tools/sessions-helpers.ts b/src/agents/tools/sessions-helpers.ts
index 3135dccd4532..9d618c8490c9 100644
--- a/src/agents/tools/sessions-helpers.ts
+++ b/src/agents/tools/sessions-helpers.ts
@@ -32,7 +32,8 @@ export {
 } from "./sessions-resolution.js";
 
 /** Coarse session category used by session list/status tools. */
-type SessionKind = "main" | "group" | "cron" | "hook" | "node" | "other";
+export const SESSION_LIST_KINDS = ["main", "group", "cron", "hook", "node", "other"] as const;
+type SessionKind = (typeof SESSION_LIST_KINDS)[number];
 
 const SESSION_KIND_BY_CLASSIFICATION: Readonly<Record<string, SessionKind>> = {
   main: "main",
diff --git a/src/agents/tools/sessions-list-tool.test.ts b/src/agents/tools/sessions-list-tool.test.ts
index ccfbefd2f532..bcc1b3dc7e06 100644
--- a/src/agents/tools/sessions-list-tool.test.ts
+++ b/src/agents/tools/sessions-list-tool.test.ts
@@ -182,6 +182,46 @@ describe("sessions-list-tool", () => {
     });
   });
 
+  it("limits session kind arguments to the documented classification values", () => {
+    const tool = createSessionsListTool({ config: VALID_CONFIG });
+
+    expect(
+      Value.Check(tool.parameters, { kinds: ["main", "group", "cron", "hook", "node", "other"] }),
+    ).toBe(true);
+    expect(Value.Check(tool.parameters, { kinds: ["unknown"] })).toBe(false);
+    expect(Value.Check(tool.parameters, { kinds: ["   "] })).toBe(false);
+  });
+
+  it.each([
+    { name: "unknown-only", kinds: ["unknown"], expected: [] },
+    { name: "whitespace-only", kinds: ["   "], expected: [] },
+    { name: "unknown scalar", kinds: "unknown", expected: [] },
+    { name: "whitespace scalar", kinds: "   ", expected: [] },
+    { name: "known scalar", kinds: "MAIN", expected: ["agent:main:main"] },
+    { name: "mixed known and unknown", kinds: ["unknown", "MAIN"], expected: ["agent:main:main"] },
+    {
+      name: "empty",
+      kinds: [],
+      expected: ["agent:main:main", "agent:main:slack:channel:team-room"],
+    },
+  ])("never broadens an explicit $name session kind filter", async ({ kinds, expected }) => {
+    mocks.gatewayCall.mockResolvedValue({
+      sessions: [
+        sessionRow("agent:main:main", "main"),
+        sessionRow("agent:main:slack:channel:team-room", "channel"),
+        sessionRow("agent:other:main", "main", "other"),
+      ],
+    });
+
+    const result = await createSessionsListTool({ config: VALID_CONFIG }).execute("filter-kinds", {
+      kinds,
+    });
+
+    expect(getSessionsListDetails(result).sessions?.map((session) => session.key)).toEqual(
+      expected,
+    );
+  });
+
   it("lists unspawned same-agent sessions from the canonical main session under tree visibility", async () => {
     mocks.resolveEffectiveSessionToolsVisibility.mockReturnValue("tree");
     mocks.resolveSandboxedSessionToolContext.mockReturnValue({
diff --git a/src/agents/tools/sessions-list-tool.ts b/src/agents/tools/sessions-list-tool.ts
index 3f67d8b4356f..8694c49ead4c 100644
--- a/src/agents/tools/sessions-list-tool.ts
+++ b/src/agents/tools/sessions-list-tool.ts
@@ -3,10 +3,7 @@
  *
  * Lists visible sessions and optionally hydrates titles, last messages, and transcript-derived metadata.
  */
-import {
-  normalizeOptionalLowercaseString,
-  readStringValue,
-} from "@openclaw/normalization-core/string-coerce";
+import { readStringValue } from "@openclaw/normalization-core/string-coerce";
 import pMap from "p-map";
 import { Type } from "typebox";
 import type { SessionRunStatus } from "../../../packages/gateway-protocol/src/schema/sessions-row.js";
@@ -21,6 +18,7 @@ import { resolveSessionAgentIds } from "../agent-scope.js";
 import {
   optionalNonNegativeIntegerSchema,
   optionalPositiveIntegerSchema,
+  stringEnum,
 } from "../schema/typebox.js";
 import {
   describeSessionLinkRule,
@@ -51,12 +49,13 @@ import {
   resolveEffectiveSessionToolsVisibility,
   resolveInternalSessionKey,
   resolveSandboxedSessionToolContext,
+  SESSION_LIST_KINDS,
   type GatewaySessionListRow,
   type SessionListRow,
 } from "./sessions-helpers.js";
 
 const SessionsListToolSchema = Type.Object({
-  kinds: Type.Optional(Type.Array(Type.String())),
+  kinds: Type.Optional(Type.Array(stringEnum(SESSION_LIST_KINDS))),
   limit: optionalPositiveIntegerSchema(),
   activeMinutes: optionalPositiveIntegerSchema(),
   messageLimit: optionalNonNegativeIntegerSchema(),
@@ -73,14 +72,7 @@ const SessionListRowOutputSchema = Type.Object(
     key: Type.String(),
     sessionId: Type.Optional(Type.String()),
     agentId: Type.String(),
-    kind: Type.Union([
-      Type.Literal("main"),
-      Type.Literal("group"),
-      Type.Literal("cron"),
-      Type.Literal("hook"),
-      Type.Literal("node"),
-      Type.Literal("other"),
-    ]),
+    kind: stringEnum(SESSION_LIST_KINDS),
     channel: Type.String(),
     archived: Type.Boolean(),
     pinned: Type.Boolean(),
@@ -185,13 +177,13 @@ export function createSessionsListTool(opts?: {
         sandboxed: opts?.sandboxed === true,
       });
 
-      const kindsRaw = readStringArrayParam(params, "kinds")
-        ?.map((value) => normalizeOptionalLowercaseString(value))
-        .filter((value): value is string => Boolean(value));
-      const allowedKindsList = (kindsRaw ?? []).filter((value) =>
-        ["main", "group", "cron", "hook", "node", "other"].includes(value),
-      );
-      const allowedKinds = allowedKindsList.length ? new Set(allowedKindsList) : undefined;
+      const kindsRaw = readStringArrayParam(params, "kinds")?.map((value) => value.toLowerCase());
+      const requestedKinds = params.kinds;
+      const allowedKinds =
+        (Array.isArray(requestedKinds) || typeof requestedKinds === "string") &&
+        requestedKinds.length > 0
+          ? new Set(kindsRaw)
+          : undefined;
 
       const limit = readPositiveIntegerParam(params, "limit");
       const activeMinutes = readPositiveIntegerParam(params, "activeMinutes");
diff --git a/test/fixtures/agents/prompt-snapshots/codex-runtime-happy-path/codex-dynamic-tools.telegram-direct.json b/test/fixtures/agents/prompt-snapshots/codex-runtime-happy-path/codex-dynamic-tools.telegram-direct.json
index e27e39c7e410..c89dc9e681b0 100644
--- a/test/fixtures/agents/prompt-snapshots/codex-runtime-happy-path/codex-dynamic-tools.telegram-direct.json
+++ b/test/fixtures/agents/prompt-snapshots/codex-runtime-happy-path/codex-dynamic-tools.telegram-direct.json
@@ -1119,6 +1119,7 @@
             },
             "kinds": {
               "items": {
+                "enum": ["main", "group", "cron", "hook", "node", "other"],
                 "type": "string"
               },
               "type": "array"
diff --git a/test/fixtures/agents/prompt-snapshots/codex-runtime-happy-path/discord-group-codex-message-tool.md b/test/fixtures/agents/prompt-snapshots/codex-runtime-happy-path/discord-group-codex-message-tool.md
index f0eed0e61210..b95d4f5ae4fc 100644
--- a/test/fixtures/agents/prompt-snapshots/codex-runtime-happy-path/discord-group-codex-message-tool.md
+++ b/test/fixtures/agents/prompt-snapshots/codex-runtime-happy-path/discord-group-codex-message-tool.md
@@ -231,8 +231,8 @@ This is the deterministic model-bound layer stack OpenClaw can snapshot for the
     "roughTokens": 0
   },
   "dynamicToolsJson": {
-    "chars": 54999,
-    "roughTokens": 13750
+    "chars": 55201,
+    "roughTokens": 13801
   },
   "openClawDeveloperInstructions": {
     "chars": 4499,
@@ -243,8 +243,8 @@ This is the deterministic model-bound layer stack OpenClaw can snapshot for the
     "roughTokens": 7221
   },
   "totalWithDynamicToolsJson": {
-    "chars": 83883,
-    "roughTokens": 20971
+    "chars": 84085,
+    "roughTokens": 21022
   },
   "userInputText": {
     "chars": 1300,
diff --git a/test/fixtures/agents/prompt-snapshots/codex-runtime-happy-path/telegram-direct-codex-message-tool.md b/test/fixtures/agents/prompt-snapshots/codex-runtime-happy-path/telegram-direct-codex-message-tool.md
index 48452daf3a5c..f7aa63deecdc 100644
--- a/test/fixtures/agents/prompt-snapshots/codex-runtime-happy-path/telegram-direct-codex-message-tool.md
+++ b/test/fixtures/agents/prompt-snapshots/codex-runtime-happy-path/telegram-direct-codex-message-tool.md
@@ -231,8 +231,8 @@ This is the deterministic model-bound layer stack OpenClaw can snapshot for the
     "roughTokens": 0
   },
   "dynamicToolsJson": {
-    "chars": 54691,
-    "roughTokens": 13673
+    "chars": 54893,
+    "roughTokens": 13724
   },
   "openClawDeveloperInstructions": {
     "chars": 3390,
@@ -243,8 +243,8 @@ This is the deterministic model-bound layer stack OpenClaw can snapshot for the
     "roughTokens": 6851
   },
   "totalWithDynamicToolsJson": {
-    "chars": 82095,
-    "roughTokens": 20524
+    "chars": 82297,
+    "roughTokens": 20575
   },
   "userInputText": {
     "chars": 929,
diff --git a/test/fixtures/agents/prompt-snapshots/codex-runtime-happy-path/telegram-heartbeat-codex-tool.md b/test/fixtures/agents/prompt-snapshots/codex-runtime-happy-path/telegram-heartbeat-codex-tool.md
index 453543ba5649..8199f59d6cce 100644
--- a/test/fixtures/agents/prompt-snapshots/codex-runtime-happy-path/telegram-heartbeat-codex-tool.md
+++ b/test/fixtures/agents/prompt-snapshots/codex-runtime-happy-path/telegram-heartbeat-codex-tool.md
@@ -226,8 +226,8 @@ This is the deterministic model-bound layer stack OpenClaw can snapshot for the
     "roughTokens": 0
   },
   "dynamicToolsJson": {
-    "chars": 56248,
-    "roughTokens": 14062
+    "chars": 56450,
+    "roughTokens": 14113
   },
   "openClawDeveloperInstructions": {
     "chars": 3390,
@@ -238,8 +238,8 @@ This is the deterministic model-bound layer stack OpenClaw can snapshot for the
     "roughTokens": 6955
   },
   "totalWithDynamicToolsJson": {
-    "chars": 84068,
-    "roughTokens": 21017
+    "chars": 84270,
+    "roughTokens": 21068
   },
   "userInputText": {
     "chars": 1271,