Tools

Reactions

The agent adds and removes emoji reactions with the message tool's react action. Behavior varies by channel.

How it works

json

{  "action": "react",  "messageId": "msg-123",  "emoji": "thumbsup"}

emoji is required when adding a reaction.
Set emoji to an empty string ("") to remove the bot's reaction(s) on channels that support it.
Set remove: true to remove one specific emoji (requires non-empty emoji).
clearAll: true is a Feishu/Lark-only flag that removes every reaction the bot placed on the message. It is paired with an empty emoji.
emoji-list is a separate message tool action, not a react parameter. It reports the emoji a channel will accept. What it returns and which per-channel action toggle enables it both vary by channel. See the channel pages under Channels.
On channels with status reactions, trackToolCalls: true on a reaction lets the runtime reuse that reacted message for the same turn's status lifecycle. Discord keeps the chosen reaction stable during work and signals actual failures, rather than cycling through tool-specific emoji.

Discord and Slack

Nextcloud Talk

Adding reactions only: emoji is required and must be non-empty.
Reaction removal is not wired to a delete call yet. remove: true is rejected with an explicit error instead of silently no-oping.
Requires the Talk bot registered with the reaction feature (see Nextcloud Talk channel docs).

Use emoji-list to find allowed standard reactions and numeric custom emoji identifiers. On Telegram, channels.telegram.actions.reactions gates both react and emoji-list, and emoji-list returns the reactions allowed in the current chat.
Empty emoji removes the bot's reactions.
remove: true also removes reactions but still requires a non-empty emoji for tool validation.

Empty emoji removes the bot reaction.
remove: true maps to empty emoji internally (still requires emoji in the tool call).
WhatsApp has one bot reaction slot per message. Sending a new reaction replaces it rather than stacking multiple emoji.

Zalo Personal (zalouser)

Feishu/Lark

Uses the same react action as other channels (add/remove/list via message reaction IDs), not a separate tool.
Adding requires non-empty emoji (mapped to a Feishu emoji_type, e.g. SMILE, THUMBSUP, HEART).
remove: true requires non-empty emoji and removes the bot's own reaction matching that emoji type.
Empty emoji with clearAll: true removes all of the bot's reactions on the message.

Signal

channels.signal.reactionNotifications controls inbound reaction notifications. "off" disables them. "own" (default) emits events when users react to bot messages. "all" emits events for all reactions. "allowlist" emits events only for senders in channels.signal.reactionAllowlist.

iMessage

Outbound reactions are iMessage tapbacks (love, like, dislike, laugh, emphasize, and question). emoji must map to one of these kinds to add a reaction.
remove: true without a recognized tapback kind removes all tapback kinds. With a recognized kind it removes just that one.

Per-channel reactionLevel throttles how often the agent sends its own reactions. Values: off, ack, minimal, or extensive.

Was this useful?