Slack ACTION
Reply to a Message Thread
Send a message as a threaded reply to an existing message. Use this when the reply should be nested under a specific message rather than posted as a new top-level message — for example, responding to a triggering event or continuing a discussion. Requires
thread_ts, the parent message's timestamp (e.g. 1403051575.000407); get it from Get Channel History or an incoming event's ts field. For a plain, non-threaded message use Post Message instead. See the documentation- Action
- Writes data
- OAuth
- SDK
- MCP
IMPLEMENTATION
Call this tool
Connect a user's Slack account once, then configure and run Reply to a Message Thread from your backend or agent.
import { PipedreamClient } from "@pipedream/sdk"
const pd = new PipedreamClient({
projectId: process.env.PIPEDREAM_PROJECT_ID!,
clientId: process.env.PIPEDREAM_CLIENT_ID!,
clientSecret: process.env.PIPEDREAM_CLIENT_SECRET!,
projectEnvironment: "production",
})
const result = await pd.actions.run({
id: "slack_v2-reply-to-a-message",
externalUserId: "{external_user_id}", // any stable ID for this user in your system
configuredProps: {
slack_v2: { authProvisionId: "apn_xxxxxxx" },
conversation: "Channel",
text: "Text",
},
})
console.log(result)curl -X POST https://api.pipedream.com/v1/connect/{project_id}/actions/run \
-H "Content-Type: application/json" \
-H "X-PD-Environment: production" \
-H "Authorization: Bearer {access_token}" \
-d '{
"external_user_id": "{external_user_id}",
"id": "slack_v2-reply-to-a-message",
"configured_props": {
"slack_v2": { "authProvisionId": "apn_xxxxxxx" },
"conversation": "Channel",
"text": "Text"
}
}'// accessToken: mint a short-lived token with the Connect SDK — see the MCP guide
const transport = new StreamableHTTPClientTransport(
new URL("https://remote.mcp.pipedream.net/v3"),
{
requestInit: {
headers: {
Authorization: `Bearer ${accessToken}`,
"x-pd-project-id": "{project_id}",
"x-pd-environment": "production",
"x-pd-external-user-id": "{external_user_id}", // any stable ID for this user in your system
"x-pd-app-slug": "slack_v2",
},
},
},
)
const mcp = new Client({ name: "my-agent", version: "1.0.0" })
await mcp.connect(transport)
const { tools } = await mcp.listTools()
// listTools() hands your model this tool's input schema, so it can
// fill the arguments itself:
const result = await mcp.callTool({
name: "slack_v2-reply-to-a-message",
arguments: {
conversation: "Channel",
text: "Text",
},
})SCHEMA
Inputs
Pipedream supplies the connected account. Your application provides the operation-specific values below. Dynamic inputs are resolved against that user's account.
| Property | Type | Description |
|---|---|---|
conversation Channel | string | Prefer a channel ID (e.g. C1234567890) — use List Channels to look it up; it resolves instantly. A channel NAME (e.g. general or #general) is also accepted, but resolving it scans up to 5 conversations.list pages (~5,000 channels), which is slow and, on large workspaces, can be rate-limited or fail with a ConfigurationError if the channel is beyond that bound — pass the ID whenever you have it. Depending on the action, this may also accept a user ID (opens a direct message) or a group DM ID — use Find User by Email / Find User by ID to resolve a user ID, or List Group Conversations for group DM IDs. Required |
text Text | string | Text of the message to send (see Slack's formatting docs). This field is usually necessary, unless you're providing only attachments instead. To mention a user, use <@U123> with their user ID. Do NOT append a display name after a pipe: Slack renders <@U123|Name> as literal text, not a mention. Required |
mrkdwn Send text as Slack mrkdwn | boolean | Optional |
as_user Send as User | boolean | Optionally pass true to post the message as the authenticated user, instead of as a bot. Defaults to false. Optional |
addToChannel Add app to channel automatically? | boolean | If true, the app will be added to the specified non-DM channel(s) automatically. If false, you must add the app to the channel manually to post to a private channel as a bot. Defaults to false. Required |
post_at Schedule message | string | Messages can only be scheduled up to 120 days in advance, and cannot be scheduled for the past. The datetime should be in ISO 8601 format. (Example: 2014-01-01T00:00:00Z) Optional |
include_sent_via_pipedream_flag Include link to Pipedream | boolean | Defaults to true, includes a link to Pipedream at the end of your Slack message. Optional |
username Bot Username | string | Optionally customize your bot's user name (default is Pipedream). Must be used in conjunction with Send as User set to false, otherwise ignored. Optional |
icon_emoji Icon (emoji) | string | Optionally provide an emoji to use as the icon for this message, wrapped in colons. E.g., :fire:. Overrides icon_url. Must be used in conjunction with Send as User set to false, otherwise ignored. Use List Icon (emoji) Options to look up valid emoji names for this workspace, including custom emoji. Optional |
icon_url Icon (image URL) | string | Optionally provide an image URL to use as the icon for this message. Must be used in conjunction with Send as User set to false, otherwise ignored. Optional |
thread_ts Thread Timestamp | string | The ts timestamp of the parent message to reply to (e.g., if triggering on new Slack messages, enter {{event.ts}}). Avoid using a reply's ts value; use its parent's instead. E.g., 1403051575.000407. Required |
thread_broadcast Send Channel Message | boolean | If true, posts in the thread and channel. Used in conjunction with Message Timestamp and indicates whether reply should be made visible to everyone in the channel. Defaults to false. Optional |
metadata_event_type Metadata Event Type | string | The name of the metadata event. Example: task_created Optional |
metadata_event_payload Metadata Event Payload | string | The payload of the metadata event. Must be a JSON string. Example: { "id": "11223", "title": "Redesign Homepage"} Optional |
unfurl_links Unfurl Links | boolean | Default to false. Pass true to enable unfurling of links. Optional |
unfurl_media Unfurl Media | boolean | Defaults to false. Pass true to enable unfurling of media content. Optional |
REFERENCE
Tool details
Behavior hints are published with the component in the Pipedream registry and surface as MCP tool annotations, so an agent can reason about a tool before it calls it.
- Registry key
- slack_v2-reply-to-a-message
- Version
- 0.2.11
- App
- Slack
- Authentication
- OAuth
- Read-only
- No
- Destructive
- No
- Open world
- Yes
- Source
- View on GitHub ↗