diff --git a/cmd/gateway.go b/cmd/gateway.go
index 55ddbc0a..f4a6c6b8 100644
--- a/cmd/gateway.go
+++ b/cmd/gateway.go
@@ -184,6 +184,8 @@ func runGateway() {
 
 	// Message tool (send to channels)
 	toolsReg.Register(tools.NewMessageTool(workspace, agentCfg.RestrictToWorkspace))
+	// Group members tool (list members in group chats)
+	toolsReg.Register(tools.NewListGroupMembersTool())
 	slog.Info("session + message tools registered")
 
 	// Register legacy tool aliases (backward-compat names from policy.go).
@@ -426,6 +428,12 @@ func runGateway() {
 			cs.SetChannelSender(channelMgr.SendToChannel)
 		}
 	}
+	// Wire group member lister on list_group_members tool
+	if t, ok := toolsReg.Get("list_group_members"); ok {
+		if gl, ok := t.(tools.GroupMemberListerAware); ok {
+			gl.SetGroupMemberLister(channelMgr.ListGroupMembers)
+		}
+	}
 
 	// Load channel instances from DB.
 	var instanceLoader *channels.InstanceLoader
diff --git a/internal/agent/loop.go b/internal/agent/loop.go
index be257b12..6e441d6e 100644
--- a/internal/agent/loop.go
+++ b/internal/agent/loop.go
@@ -7,6 +7,7 @@ import (
 	"log/slog"
 	"os"
 	"path/filepath"
+	"slices"
 	"sort"
 	"strings"
 	"sync"
@@ -628,6 +629,22 @@ func (l *Loop) runLoop(ctx context.Context, req RunRequest) (*RunResult, error)
 			toolDefs = filtered
 		}
 
+		// Hide channel-specific tools when channel type doesn't match.
+		if req.ChannelType != "" {
+			filtered := toolDefs[:0:0]
+			for _, td := range toolDefs {
+				if tool, ok := l.tools.Get(td.Function.Name); ok {
+					if ca, ok := tool.(tools.ChannelAware); ok {
+						if !slices.Contains(ca.RequiredChannelTypes(), req.ChannelType) {
+							continue
+						}
+					}
+				}
+				filtered = append(filtered, td)
+			}
+			toolDefs = filtered
+		}
+
 		// Use per-request model override if set (e.g. heartbeat uses cheaper model).
 		model := l.model
 		if req.ModelOverride != "" {
diff --git a/internal/channels/channel.go b/internal/channels/channel.go
index 28e350ba..dcfb3807 100644
--- a/internal/channels/channel.go
+++ b/internal/channels/channel.go
@@ -330,6 +330,17 @@ func (c *BaseChannel) HandleMessage(senderID, chatID, content string, media []st
 	c.bus.PublishInbound(msg)
 }
 
+// GroupMember represents a member of a group chat.
+type GroupMember struct {
+	MemberID string `json:"member_id"`
+	Name     string `json:"name"`
+}
+
+// GroupMemberProvider is optionally implemented by channels that can list group members.
+type GroupMemberProvider interface {
+	ListGroupMembers(ctx context.Context, chatID string) ([]GroupMember, error)
+}
+
 // PendingCompactable is optionally implemented by channels that have a PendingHistory
 // supporting LLM-based compaction. InstanceLoader uses this to wire compaction config
 // after channel creation.
diff --git a/internal/channels/feishu/feishu.go b/internal/channels/feishu/feishu.go
index 1c5e2d76..da87c40e 100644
--- a/internal/channels/feishu/feishu.go
+++ b/internal/channels/feishu/feishu.go
@@ -10,6 +10,7 @@ import (
 	"fmt"
 	"log/slog"
 	"net/http"
+	"regexp"
 	"strings"
 	"sync"
 	"time"
@@ -395,23 +396,67 @@ func resolveReceiveIDType(id string) string {
 
 // --- Content builders ---
 
+// mentionRe matches @ou_xxx patterns (Lark open_id) for outbound mention conversion.
+var mentionRe = regexp.MustCompile(`@(ou_[a-zA-Z0-9_]+)`)
+
+// hasMentions checks if text contains @ou_xxx patterns.
+func hasMentions(text string) bool {
+	return mentionRe.MatchString(text)
+}
+
+// buildPostContent creates a Lark "post" message body.
+// If the text contains @ou_xxx patterns, they are converted to native "at" elements
+// so Lark renders real @mentions with notifications.
 func buildPostContent(text string) string {
+	var elements []map[string]any
+
+	if hasMentions(text) {
+		// Split text around @ou_xxx patterns → alternating md + at elements.
+		matches := mentionRe.FindAllStringIndex(text, -1)
+		prev := 0
+		for _, loc := range matches {
+			// Text before the mention
+			if loc[0] > prev {
+				elements = append(elements, map[string]any{
+					"tag":  "md",
+					"text": text[prev:loc[0]],
+				})
+			}
+			// The mention itself: extract ou_xxx from "@ou_xxx"
+			userID := text[loc[0]+1 : loc[1]] // skip "@"
+			elements = append(elements, map[string]any{
+				"tag":     "at",
+				"user_id": userID,
+			})
+			prev = loc[1]
+		}
+		// Remaining text after last mention
+		if prev < len(text) {
+			elements = append(elements, map[string]any{
+				"tag":  "md",
+				"text": text[prev:],
+			})
+		}
+	} else {
+		elements = []map[string]any{{"tag": "md", "text": text}}
+	}
+
 	content := map[string]any{
 		"zh_cn": map[string]any{
-			"content": [][]map[string]any{
-				{
-					{
-						"tag":  "md",
-						"text": text,
-					},
-				},
-			},
+			"content": [][]map[string]any{elements},
 		},
 	}
 	data, _ := json.Marshal(content)
 	return string(data)
 }
 
+// convertMentionsForCard replaces @ou_xxx in text with Lark card markdown mention tags.
+// e.g. "@ou_abc123" → "<at id=ou_abc123></at>"
+// This syntax works in interactive card markdown content.
+func convertMentionsForCard(text string) string {
+	return mentionRe.ReplaceAllString(text, `<at id=$1></at>`)
+}
+
 func buildMarkdownCard(text string) map[string]any {
 	return map[string]any{
 		"schema": "2.0",
@@ -422,7 +467,7 @@ func buildMarkdownCard(text string) map[string]any {
 			"elements": []map[string]any{
 				{
 					"tag":     "markdown",
-					"content": text,
+					"content": convertMentionsForCard(text),
 				},
 			},
 		},
@@ -507,7 +552,30 @@ func (c *Channel) removeTypingReaction(ctx context.Context, chatID string) error
 	return nil
 }
 
-// Ensure Channel implements the channels.Channel, WebhookChannel, and ReactionChannel interfaces at compile time.
+// ListGroupMembers returns all members of a Lark group chat.
+// Also syncs discovered members into the contact store (if available).
+func (c *Channel) ListGroupMembers(ctx context.Context, chatID string) ([]channels.GroupMember, error) {
+	members, err := c.client.ListChatMembers(ctx, chatID)
+	if err != nil {
+		slog.Warn("feishu.list_group_members", "chat_id", chatID, "error", err)
+		return nil, err
+	}
+	result := make([]channels.GroupMember, len(members))
+	for i, m := range members {
+		result[i] = channels.GroupMember{
+			MemberID: m.MemberID,
+			Name:     m.Name,
+		}
+		// Auto-sync member into contact store
+		if cc := c.ContactCollector(); cc != nil {
+			cc.EnsureContact(ctx, channels.TypeFeishu, c.Name(), m.MemberID, m.MemberID, m.Name, "", "group")
+		}
+	}
+	return result, nil
+}
+
+// Ensure Channel implements the channels.Channel, WebhookChannel, ReactionChannel, and GroupMemberProvider interfaces at compile time.
 var _ channels.Channel = (*Channel)(nil)
 var _ channels.WebhookChannel = (*Channel)(nil)
 var _ channels.ReactionChannel = (*Channel)(nil)
+var _ channels.GroupMemberProvider = (*Channel)(nil)
diff --git a/internal/channels/feishu/larkclient_messaging.go b/internal/channels/feishu/larkclient_messaging.go
index f5ecf300..3146ff5e 100644
--- a/internal/channels/feishu/larkclient_messaging.go
+++ b/internal/channels/feishu/larkclient_messaging.go
@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"log/slog"
+	"net/url"
 	"strconv"
 )
 
@@ -252,6 +253,57 @@ func (c *LarkClient) GetBotInfo(ctx context.Context) (string, error) {
 	return result.Bot.OpenID, nil
 }
 
+// --- IM API: Chat Members ---
+
+// ChatMember represents a member of a Lark group chat.
+type ChatMember struct {
+	MemberID     string `json:"member_id"`
+	MemberIDType string `json:"member_id_type"`
+	Name         string `json:"name"`
+	TenantKey    string `json:"tenant_key"`
+}
+
+// ListChatMembers returns all members of a group chat, handling pagination automatically.
+// Lark API: GET /open-apis/im/v1/chats/{chat_id}/members
+// Requires scope: im:chat.members:read
+func (c *LarkClient) ListChatMembers(ctx context.Context, chatID string) ([]ChatMember, error) {
+	var all []ChatMember
+	pageToken := ""
+
+	for {
+		path := fmt.Sprintf("/open-apis/im/v1/chats/%s/members?member_id_type=open_id&page_size=100", url.PathEscape(chatID))
+		if pageToken != "" {
+			path += "&page_token=" + url.QueryEscape(pageToken)
+		}
+
+		resp, err := c.doJSON(ctx, "GET", path, nil)
+		if err != nil {
+			return nil, err
+		}
+		if resp.Code != 0 {
+			return nil, fmt.Errorf("list chat members: code=%d msg=%s", resp.Code, resp.Msg)
+		}
+
+		var result struct {
+			Items     []ChatMember `json:"items"`
+			PageToken string       `json:"page_token"`
+			HasMore   bool         `json:"has_more"`
+		}
+		if err := json.Unmarshal(resp.Data, &result); err != nil {
+			return nil, fmt.Errorf("unmarshal response: %w", err)
+		}
+
+		all = append(all, result.Items...)
+
+		if !result.HasMore || result.PageToken == "" {
+			break
+		}
+		pageToken = result.PageToken
+	}
+
+	return all, nil
+}
+
 // --- Contact API ---
 
 func (c *LarkClient) GetUser(ctx context.Context, userID, userIDType string) (string, error) {
diff --git a/internal/channels/manager.go b/internal/channels/manager.go
index 82f1a486..33846bd8 100644
--- a/internal/channels/manager.go
+++ b/internal/channels/manager.go
@@ -2,6 +2,7 @@ package channels
 
 import (
 	"context"
+	"fmt"
 	"log/slog"
 	"sync"
 
@@ -190,6 +191,21 @@ func (m *Manager) ChannelTypeForName(name string) string {
 	return ""
 }
 
+// ListGroupMembers delegates to the channel's GroupMemberProvider if available.
+func (m *Manager) ListGroupMembers(ctx context.Context, channelName, chatID string) ([]GroupMember, error) {
+	m.mu.RLock()
+	ch, ok := m.channels[channelName]
+	m.mu.RUnlock()
+	if !ok {
+		return nil, fmt.Errorf("channel %q not found", channelName)
+	}
+	gmp, ok := ch.(GroupMemberProvider)
+	if !ok {
+		return nil, fmt.Errorf("channel %q does not support listing group members", channelName)
+	}
+	return gmp.ListGroupMembers(ctx, chatID)
+}
+
 // UnregisterChannel removes a channel from the manager.
 func (m *Manager) UnregisterChannel(name string) {
 	m.mu.Lock()
diff --git a/internal/tools/group_members.go b/internal/tools/group_members.go
new file mode 100644
index 00000000..ed4bc2d8
--- /dev/null
+++ b/internal/tools/group_members.go
@@ -0,0 +1,97 @@
+package tools
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+
+	"github.com/nextlevelbuilder/goclaw/internal/channels"
+)
+
+// GroupMemberLister abstracts listing members of a group chat.
+// Implemented by channels.Manager.ListGroupMembers.
+type GroupMemberLister func(ctx context.Context, channel, chatID string) ([]channels.GroupMember, error)
+
+// GroupMemberListerAware tools can receive a group member lister function.
+type GroupMemberListerAware interface {
+	SetGroupMemberLister(GroupMemberLister)
+}
+
+// ListGroupMembersTool allows the agent to list members in a group chat.
+type ListGroupMembersTool struct {
+	lister GroupMemberLister
+}
+
+func NewListGroupMembersTool() *ListGroupMembersTool {
+	return &ListGroupMembersTool{}
+}
+
+func (t *ListGroupMembersTool) SetGroupMemberLister(l GroupMemberLister) { t.lister = l }
+
+func (t *ListGroupMembersTool) RequiredChannelTypes() []string { return []string{"feishu"} }
+
+func (t *ListGroupMembersTool) Name() string { return "list_group_members" }
+func (t *ListGroupMembersTool) Description() string {
+	return "List all members of the current group chat. Returns member IDs (open_id) and display names. Only works in group conversations on supported channels (Lark/Feishu). Use this to find out who is in the group, check attendance, or identify members. To @mention a member in a message, use @member_id (e.g. @ou_abc123) — it will be converted to a native mention with notification."
+}
+
+func (t *ListGroupMembersTool) Parameters() map[string]any {
+	return map[string]any{
+		"type": "object",
+		"properties": map[string]any{
+			"channel": map[string]any{
+				"type":        "string",
+				"description": "Channel name (default: current channel from context)",
+			},
+			"chat_id": map[string]any{
+				"type":        "string",
+				"description": "Group chat ID (default: current chat from context)",
+			},
+		},
+		"required": []string{},
+	}
+}
+
+func (t *ListGroupMembersTool) Execute(ctx context.Context, args map[string]any) *Result {
+	if t.lister == nil {
+		return ErrorResult("list_group_members: no group member lister available")
+	}
+
+	channel, _ := args["channel"].(string)
+	if channel == "" {
+		channel = ToolChannelFromCtx(ctx)
+	}
+	if channel == "" {
+		return ErrorResult("channel is required (no current channel in context)")
+	}
+
+	chatID, _ := args["chat_id"].(string)
+	if chatID == "" {
+		chatID = ToolChatIDFromCtx(ctx)
+	}
+	if chatID == "" {
+		return ErrorResult("chat_id is required (no current chat in context)")
+	}
+
+	members, err := t.lister(ctx, channel, chatID)
+	if err != nil {
+		return ErrorResult(fmt.Sprintf("failed to list group members: %v", err))
+	}
+
+	type memberOut struct {
+		MemberID string `json:"member_id"`
+		Name     string `json:"name"`
+	}
+	out := make([]memberOut, len(members))
+	for i, m := range members {
+		out[i] = memberOut{MemberID: m.MemberID, Name: m.Name}
+	}
+
+	data, _ := json.Marshal(map[string]any{
+		"channel": channel,
+		"chat_id": chatID,
+		"count":   len(out),
+		"members": out,
+	})
+	return NewResult(string(data))
+}
diff --git a/internal/tools/policy.go b/internal/tools/policy.go
index c664280b..6b276754 100644
--- a/internal/tools/policy.go
+++ b/internal/tools/policy.go
@@ -21,7 +21,7 @@ var toolGroups = map[string][]string{
 	"sessions":   {"sessions_list", "sessions_history", "sessions_send", "spawn", "session_status"},
 	"ui":         {"browser"},
 	"automation": {"cron"},
-	"messaging":  {"message", "create_forum_topic"},
+	"messaging":  {"message", "create_forum_topic", "list_group_members"},
 	"team": {"team_tasks", "team_message"},
 	// Composite group: all goclaw native tools (excludes MCP/custom plugins).
 	"goclaw": {
@@ -29,7 +29,7 @@ var toolGroups = map[string][]string{
 		"web_search", "web_fetch", "browser",
 		"memory_search", "memory_get",
 		"sessions_list", "sessions_history", "sessions_send", "spawn", "session_status",
-		"cron", "message", "create_forum_topic",
+		"cron", "message", "create_forum_topic", "list_group_members",
 		"read_image", "read_document", "read_audio", "read_video",
 		"create_image", "create_video",
 		"skill_search", "mcp_tool_search", "tts",
diff --git a/internal/tools/types.go b/internal/tools/types.go
index b291f16e..7c2615d3 100644
--- a/internal/tools/types.go
+++ b/internal/tools/types.go
@@ -99,6 +99,12 @@ type ChannelSenderAware interface {
 	SetChannelSender(ChannelSender)
 }
 
+// ChannelAware is optionally implemented by tools that only work on specific channel types.
+// Tools implementing this are filtered out when the current channel type doesn't match.
+type ChannelAware interface {
+	RequiredChannelTypes() []string
+}
+
 // ToProviderDef converts a Tool to a providers.ToolDefinition for LLM APIs.
 func ToProviderDef(t Tool) providers.ToolDefinition {
 	return providers.ToolDefinition{
diff --git a/ui/web/src/pages/channels/channel-schemas.ts b/ui/web/src/pages/channels/channel-schemas.ts
index 6bba6521..f6d543b9 100644
--- a/ui/web/src/pages/channels/channel-schemas.ts
+++ b/ui/web/src/pages/channels/channel-schemas.ts
@@ -182,6 +182,7 @@ export const requiredScopes: Partial<Record<string, ScopeEntry[]>> = {
     { scope: "contact:user.employee_id:readonly", note: "Range: All members" },
     { scope: "event:ip_list" },
     { scope: "im:chat.members:bot_access" },
+    { scope: "im:chat.members:read", note: "Required for list_group_members tool" },
     { scope: "im:message" },
     { scope: "im:message.group_at_msg:readonly" },
     { scope: "im:message.p2p_msg:readonly" },