slack.messages.send_message

Send a message to a Slack channel

Send a message to a Slack channel using the chat.postMessage API.

Inputs:

• channel: Channel ID or name, e.g. C01234567 or #general (required).

• text: Message text (required). Supports Slack mrkdwn formatting.

• username: Override bot display name (optional).

• icon_emoji: Override bot emoji icon, e.g. :robot_face: (optional).

• thread_ts: Thread timestamp to reply in a thread (optional).

• blocks: Slack Block Kit blocks as JSON list (optional — overrides text for display).

• connection_uuid: Slack CloudConnection UUID (optional). The customer's OAuth bot token is read from this connection. Defaults to the organization's active Slack connection when omitted.

Outputs (terminal state_data):

• message_ts: str — message timestamp (use as thread_ts to reply)
• channel: str — channel ID where the message was posted

Token resolution: the bot token comes from the customer's Slack CloudConnection (per-organization OAuth token) via context.get_plugin("slack"), NOT a static app token. A static plugin token, if configured, is only a single-tenant/test fallback.

Overview

Property	Value
Workflow type	Atomic
Library	App-slack
Version	1.0

Input Schema

Field	Type	Required	Default	Description
channel	string	Yes	—	Channel ID or name, e.g. C01234567 or #general
text	string	Yes	—	Message text (mrkdwn supported)
username	string	No	—	Override bot display name
icon_emoji	string	No	—	Override bot emoji icon, e.g. :robot_face:
thread_ts	string	No	—	Thread timestamp to reply in a thread
blocks	json	No	—	Slack Block Kit blocks list
connection_uuid	uuid	No	—	Slack CloudConnection UUID (per-organization OAuth token); defaults to the organization's active Slack connection

Output Schema

Field	Type	Required	Default	Description
channel	string	No	—	—
message_ts	string	No	—	—
blocks	json	No	—	—
connection_uuid	uuid	No	—	—
icon_emoji	string	No	—	—
text	string	No	—	—
thread_ts	string	No	—	—
username	string	No	—	—
failure_reason	string	No	—	—
failure_type	string	No	—	—
failed_action	string	No	—	—
failed_at_state	string	No	—	—
failed_step	string	No	—	—
failed_layer	string	No	—	—
error	string	No	—	—
error_type	string	No	—	—

States

State	Initial	Terminal	Success	Auto-advance	Description
pending	Yes	No	—	execute	—
completed	No	Yes	Yes	—	—
failed	No	Yes	No	—	—

State Diagram

Transitions

From	Action	To	Description
pending	execute	completed	—
* (any state)	fail	failed	—

API Usage

POST /api/workflows/start
Content-Type: application/json

{
  "workflow_type": "slack.messages.send_message",
  "initial_data": {
    "channel": "value",
    "text": "value"
  }
}