reaction attaches an emoji to the message the agent is replying to, the way a person taps and holds a message. It can be the whole reply: a reply that contains only a reaction sends no text, which is how to close a conversation without inviting another turn. It renders natively on WhatsApp, Instagram, Messenger, Slack, iMessage, and the web widget; the platform teaches the block but doesn’t tell the model it works in the widget, so say so in your instructions when you want it there. See Response formatting for the per-channel matrix.
Verified against lua-cli 3.33.0.
Syntax
Fields
Example
A reaction with a short text reply; the emoji lands on the end user’s message and the text arrives as usual.Where it renders
Pick common emoji: on Messenger, Slack, and iMessage an emoji with no mapping is appended to the reply as text instead of reacting.
See also
- Response formatting — the per-channel matrix
- Slack — app scopes
- actions — when the end user should choose rather than be acknowledged

