Slack Action

Posts and manages Slack from a flow. Sixteen operations across messages, channels, reactions, users and files — including the two that people usually reach for a bot to get: an ephemeral message only one person sees, and a message scheduled for later.

Setup

Pick a Slack credential — an OAuth connection or an incoming webhook. A webhook can post to the channel it was created for and nothing else, so choosing it narrows the operation list accordingly.

Mode — action or AI toolkit

The Mode selector decides who drives the node. In Action mode you pick one operation and fill its fields, and the node does that every time it runs. In AI toolkit mode the operations become tools an AI Node can call, and the model chooses which one and with what arguments.

ℹToolkit mode is opt-in per node, and it is what makes this node show up in an AI Node's tool picker. A node left in Action mode is invisible to agents.

Operations

The Operation dropdown decides what the node does and which fields appear under it. These are the exact values the API validates against:

Value	In the dropdown	What it does
sendMessage	Send message	Post a message to a channel, group, or DM.
updateMessage	Update message	Edit a message the bot posted earlier.
deleteMessage	Delete message	Delete a message the bot posted earlier.
sendEphemeral	Send ephemeral	Post a message visible only to a single user (the rest of the channel does not see it).
scheduleMessage	Schedule message	Schedule a message to be posted at a future time.
getMessage	Get message	Fetch a single message by its timestamp.
listChannels	List channels	List public + private channels the bot can see in the workspace.
getChannelHistory	Get channel history	Read recent messages from a channel.
getThreadReplies	Get thread replies	Fetch replies to a thread.
createChannel	Create channel	Create a new public or private channel.
inviteToChannel	Invite to channel	Invite one or more users to a channel.
addReaction	Add reaction	Add an emoji reaction to a message.
removeReaction	Remove reaction	Remove an emoji reaction from a message.
listUsers	List users	List human members of the workspace (excludes deleted users + bots by default).
getUserInfo	Get user info	Fetch a user profile (name, email, timezone, status).
uploadFile	Upload file	Upload a file (PDF, image, anything) and optionally share it in a channel.

Gotchas

The bot has to be in the channel. A bot that has not joined gets not_in_channel, and no permission scope fixes it — invite the app to the channel.
Editing and deleting only work on the bot's own messages.
ts is the message id. Slack identifies messages by timestamp, so keep the ts a send returns if you plan to edit, delete or thread onto it.
Thread replies use threadTs, the parent's ts — not the reply's.
Blocks beat text. Passing blocks gives you the layout; text is still worth filling because it is what notifications show.