Lark Im

im (v1)

Core Concepts

• Message: A single message in a chat, identified by message_id (omxxx). Supports types: text, post, image, file, audio, video, sticker, interactive (card), sharechat, shareuser, mergeforward, etc.
• Chat: A group chat or P2P conversation, identified by chat_id (oc_xxx).
• Thread: A reply thread under a message, identified by thread_id (omxxx or omtxxx).
• Reaction: An emoji reaction on a message.
• Flag: A bookmark on a message or thread.
• Feed Shortcut: A chat pinned to the current user's feed sidebar, identified by feed_card_id (an oc_xxx openchatid for CHAT type).
• Feed Group: A tag that groups feed cards in the feed list, identified by feed_group_id (ofg_xxx). Members are feed cards, each identified by feed_id + feed_type. Two types: normal (members managed explicitly) and rule (members auto-derived from rules).

Resource Relationships

Chat (oc_xxx)
├── Message (om_xxx)
│   ├── Thread (reply thread)
│   ├── Reaction (emoji)
│   └── Resource (image / file / video / audio)
└── Member (user / bot)

Important Notes

Identity and Token Mapping

• User identity uses user_access_token. Calls run as the authorized end user, so permissions depend on both the app scopes and that user's own access to the target chat/message/resource.
• Bot identity uses tenant_access_token. Calls run as the app bot, so behavior depends on the bot's membership, app visibility, availability range, and bot-specific scopes.
• If an IM API says it supports both user and bot, the token type changes who the operator is. The same API can succeed with one identity and fail with the other because owner/admin status, chat membership, tenant boundary, or app availability are checked against the current caller.

Sender Name Resolution

When fetching messages (lark_im_chat_messages_list, lark_im_threads_messages_list, lark_im_messages_mget, lark_im_messages_search), a display name is returned for both user and bot senders:

• Server-provided name: the read APIs return sender_name (plus the full-i18n sender_i18n_names map) on each message sender; it is surfaced as the sender's name for users and bots alike. No name lookup and no extra permission are needed — no contact scope and no application:bot.basic_info:read.
• Fallback to id: when the server does not provide a name, the sender is shown by its id and the operation still succeeds. There is no contact-directory fallback.

The raw sender_name is not duplicated in output (its value is in name); the full sender_i18n_names map (all locales) is preserved for consumers that need a specific language, alongside an optional open_bot_id (ou_) for bot senders aligned with the message-receive event channel. System messages (msg_type: system) have no sender name — that is normal, not an error.

Default message enrichment (reactions / update_time)

The four message-pulling shortcuts (lark_im_messages_mget, lark_im_chat_messages_list, lark_im_messages_search, lark_im_threads_messages_list) automatically attach a reactions block and (for edited messages) update_time to each returned message — no separate im.reactions.batch_query call is needed. Pass no_reactions=true to opt out. For the full contract (output shape, the im:message.reactions:read scope requirement, and the "missing field ≠ fetch failure" data rules), call lark_get_skill(domain="im", section="message-enrichment").

Opt-in resource auto-download (download_resources)

lark_im_chat_messages_list, lark_im_messages_mget, and lark_im_threads_messages_list accept download_resources=true (off by default — no resources block and no extra requests when omitted). When set, eligible message resources (image/file/audio/video/media + post-embedded; stickers excluded) are downloaded into ./lark-im-resources/ and each message gains a resources array of {message_id, key, type, local_path, size_bytes}. Downloads are deduped by (message_id, file_key), run with bounded concurrency, and isolate single-resource failures (error: true + stderr warning). Scope: requires im:message:readonly (already declared by the listing commands — no extra scope); works under both user and bot identity. For one-off downloads use lark_im_messages_resources_download. Full contract: lark_get_skill(domain="im", section="message-enrichment").

Card Messages (Interactive)

Before sending or replying with any interactive card (lark_im_messages_send / lark_im_messages_reply), you MUST call lark_get_skill(domain="im", section="card/lark-im-card-create") and follow its workflow. The card JSON passed to msg_type="interactive" + content must be the output of that workflow — never hand-write or copy a card payload.

Card messages (interactive type) are not yet supported for compact conversion in event subscriptions. The raw event data will be returned instead, with a hint printed to stderr.

interactive cards support callback events (card.action.trigger). ⚠️ Card callbacks require bot identity (event consumption + delayed-update API both need tenant_access_token) and are not available via the MCP server, which is user-identity only. Background: lark_get_skill(domain="im", section="card-action-reply").

Audio Messages

audio sends a voice message and supports only Opus audio files, for example .opus files or Ogg Opus (.ogg) files. For mp3, wav, or other non-Opus audio, either convert to .opus first and keep using audio, or send the original file as an attachment with file.

Sending Doc Content as a Message

When sending content fetched from a Lark doc as a message, fetch the doc with doc_format="im-markdown", then send it as a message using the markdown format. The fetched content is already in markdown; in any content-forwarding scenario, keep the fetched original text and send it in the markdown format. Note: if the doc contains a cite tag with type="user", keep it as-is and do not strip the tag.

Flag Types

Flags support two layers:

• Message-layer flag: (ItemTypeDefault, FlagTypeMessage) — regular message bookmark
• Feed-layer flag: (ItemTypeThread/ItemTypeMsgThread, FlagTypeFeed) — thread as feed-layer bookmark

Item types for feed-layer flags:

• ItemTypeThread (4) = thread in a topic-style chat
• ItemTypeMsgThread (11) = thread in a regular chat

Feed Shortcut

Feed shortcuts add chats to the current user's feed sidebar. They are distinct from flags:

• Flag = bookmark on a message/thread, scoped to the user's bookmark list.
• Feed shortcut = entry in the user's feed sidebar (currently only chats).

Key limits:

• Only CHAT-type (feed_card_id is oc_xxx) is exposed via OpenAPI; doc/app/subscription shortcuts exist internally but are not yet whitelisted.
• All three operations (create/remove/list) are user-identity only — they sign with user_access_token.
• Batch size is 10 per call for create/remove; list is a one-page wrapper with opaque page_token pagination.

Shortcuts（推荐优先使用）

Shortcut 是对常用操作的高级封装。有 Shortcut 的操作优先使用。

| Shortcut | 说明 | |----------|------| | lark_get_skill(domain="im", section="chat-create") | Create a group chat or topic chat; user/bot; chatmode group|topic; private/public; invites users/bots; optionally sets bot manager | | lark_get_skill(domain="im", section="chat-list") | List chats the current user/bot is a member of; defaults to groups; pass types=p2p,group to include p2p single chats (user-only); user/bot; supports sorting, pagination, excludemuted (user-only) | | lark_get_skill(domain="im", section="chat-members-list") | List members of a chat; returns separate users[] / bots[] buckets; callable as user or bot; membertypes filters which kinds to return; pageall pagination; surfaces truncations[] when the server caps a bucket | | lark_get_skill(domain="im", section="chat-messages-list") | List messages in a chat or P2P conversation; user/bot; accepts chatid or userid, resolves P2P chatid, supports time range/sort/pagination | | lark_get_skill(domain="im", section="chat-search") | Search visible group chats by query keyword and/or memberids; user/bot; e.g. look up chatid by group name; supports type filters, sorting, pagination, and excludemuted (user identity only) | | lark_get_skill(domain="im", section="chat-update") | Update group chat name or description; user/bot; updates a chat's name or description | | lark_get_skill(domain="im", section="messages-mget") | Batch get messages by IDs; user/bot; fetches up to 50 om message IDs, formats sender names, expands thread replies | | lark_get_skill(domain="im", section="messages-reply") | Reply to a message (supports thread replies); user/bot; supports text/markdown/post/media replies, reply-in-thread, idempotency key | | lark_get_skill(domain="im", section="messages-resources-download") | Download images/files from a message; user/bot; supports automatic chunked download for large files (8MB chunks), auto-detects file extension from Content-Type | | lark_get_skill(domain="im", section="messages-search") | Search messages across chats (supports keyword, sender, time range filters) with user identity; user-only; filters by chat/sender/attachment/time, supports auto-pagination via page_all / page_limit, enriches results via batched mget and chats batchquery | | lark_get_skill(domain="im", section="messages-send") | Send a message to a chat or direct message; user/bot; sends to chatid or userid with text/markdown/post/media, supports idempotency key | | lark_get_skill(domain="im", section="threads-messages-list") | List messages in a thread; user/bot; accepts om/omt input, resolves message IDs to threadid, supports sort/pagination | | lark_get_skill(domain="im", section="flag-create") | Create a bookmark on a message; user-only; defaults to message-layer flag; use flagtype="feed" for feed-layer flag (itemtype auto-detected from chat mode) | | lark_get_skill(domain="im", section="flag-cancel") | Cancel (remove) a bookmark. When no flagtype is given, best-effort double-cancel: removes message layer and (when chattype is determinable) feed layer | | lark_get_skill(domain="im", section="flag-list") | List bookmarks; user-only; auto-enriches feed-type thread entries with message content; page_all is capped by page_limit (default 20, max 1000), and has_more=true means the result is incomplete | | lark_get_skill(domain="im", section="feed-shortcut-create") | Add chats to the user's feed shortcuts; user-only; ocxxx chat IDs only; batch up to 10 per call; head/tail controls insertion order; partial failures return an ok:false ledger | | lark_get_skill(domain="im", section="feed-shortcut-remove") | Remove chats from the user's feed shortcuts; user-only; batch up to 10 per call; removing an absent shortcut is idempotent success; real per-item failures return an ok:false ledger | | lark_get_skill(domain="im", section="feed-shortcut-list") | List one page of the user's feed shortcuts; user-only; omit page_token for the first page; default output enriches CHAT entries under detail; pass no_detail=true to skip the extra lookup and im:chat:read scope | | lark_get_skill(domain="im", section="feed-group-list") | List the caller's feed groups (tags); user-only; supports page_all auto-pagination | | lark_get_skill(domain="im", section="feed-group-list-item") | List feed cards in a feed group (tag); user-only; enriches each item with chatname resolved from feedid; supports pageall auto-pagination | | lark_get_skill(domain="im", section="feed-group-query-item") | Look up specific feed cards in a feed group (tag) by ID; user-only; enriches each item with chatname resolved from feed_id |

API Resources

lark_discover(query="im..")   # 调用 API 前必须先查看参数结构
lark_invoke(tool_name="lark_im__", args={...}) # 调用 API

> 重要：使用原生 API 时，必须先调用 lark_discover 查看 data / params 参数结构，不要猜测字段格式。

chats

• create — 创建群。Identity: bot only (tenant_access_token). ⚠️ This operation requires bot identity and is not available via the MCP server.
• get — 获取群信息。Identity: supports user and bot; the caller must be in the target chat to get full details, and must belong to the same tenant for internal chats.
• link — 获取群分享链接。Identity: supports user and bot; the caller must be in the target chat, must be an owner or admin when chat sharing is restricted to owners/admins, and must belong to the same tenant for internal chats.
• update — 更新群信息。Identity: supports user and bot.

chat.members

• create — 将用户或机器人拉入群聊。Identity: supports user and bot; the caller must be in the target chat; for bot calls, added users must be within the app's availability; for internal chats the operator must belong to the same tenant; if only owners/admins can add members, the caller must be an owner/admin, or a chat-creator bot with im:chat:operate_as_owner.
• delete — 将用户或机器人移出群聊。Identity: supports user and bot; only group owner, admin, or creator bot can remove others; max 50 users or 5 bots per request.

chat.user_setting

• batch_query — 批量查询当前用户在群内的个人偏好设置 (e.g. is_muted mutes normal messages, is_mute_at_all mutes @all messages); up to 10 chats per request. Identity: user only (user_access_token); the caller must be in each target chat.
• batch_update — 批量更新当前用户在群内的个人偏好设置 (e.g. is_muted mutes normal messages, is_mute_at_all mutes @all messages); up to 10 chats per request. Identity: user only (user_access_token); the caller must be in each target chat.

chat.nickname

• get — 获取自己的群昵称。Get your own nickname in the chat (self-only). Identity: user only (user_access_token); returns an empty string when no nickname is set.
• update — 设置自己的群昵称。Set or update your own nickname in the chat (self-only). Identity: user only (user_access_token); nickname must be a non-empty string (max 300 bytes). Use DELETE to clear it.
• delete — 清空自己的群昵称。Clear your own nickname in the chat (self-only). Identity: user only (user_access_token).

chat.managers

• add_managers — 指定群管理员。Identity: supports user and bot; only the group owner can add managers; max 10 managers per chat (20 for super-large chats), and at most 5 bots per request.
• delete_managers — 删除群管理员。Identity: supports user and bot; only the group owner can remove managers; max 50 users or 5 bots per request.

chat.moderation

• get — 获取群成员发言权限。Identity: supports user and bot; the caller must be in the target chat and belong to the same tenant.
• update — 更新群发言权限。Identity: supports user and bot; only the group owner (or creator bot with im:chat:operate_as_owner) can update; the caller must be in the chat.

messages

• delete — 撤回消息。Identity: supports user and bot; for bot calls, the bot must be in the chat to revoke group messages; to revoke another user's group message, the bot must be the owner, an admin, or the creator; for user P2P recalls, the target user must be within the bot's availability.
• forward — 转发消息。Identity: supports user and bot.
• merge_forward — 合并转发消息。⚠️ This operation requires bot identity and is not available via the MCP server.
• read_users — 查询消息已读信息。⚠️ This operation requires bot identity and is not available via the MCP server.
• urgent_app — 发送应用内加急。⚠️ This operation requires bot identity and is not available via the MCP server.
• urgent_phone — 发送电话加急。⚠️ This operation requires bot identity and is not available via the MCP server.
• urgent_sms — 发送短信加急。⚠️ This operation requires bot identity and is not available via the MCP server.

reactions

• batch_query — 批量获取消息表情。Identity: supports user and bot. [Must-read] `larkgetskill(domain="im", section="re

…

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: aws-samples
• Source: aws-samples/sample-lark-mcp-on-agentcore
• License: MIT-0

Install and usage instructions live in the source repository linked above.