What you unlock
Messaging and search
Send, schedule, and search messages across channels, threads, and direct messages.
Channel management
Create, archive, rename channels, invite users, and manage topics and purposes.
File and media sharing
Upload, download, share, and manage files directly within Slack conversations.
9 real-time triggers
Start an agent task automatically when messages arrive, reactions are added, channels are created, and more.
Connect Slack
Authorize with Slack
Click Connect and sign in to your Slack workspace. Approve the requested permissions to let Mantle read and
write messages on your behalf.
Agent tools
Messages
| Tool | Description |
|---|---|
| Send message | Post a message to a channel or conversation |
| Send ephemeral message | Send a message visible only to one user |
| Update message | Edit an existing message |
| Delete message | Remove a message from a channel |
| Schedule message | Schedule a message for future delivery |
| Fetch conversation history | Retrieve recent messages from a channel |
| Fetch thread replies | Get all replies in a message thread |
Search
| Tool | Description |
|---|---|
| Search messages | Search messages across the workspace |
| Search all content | Search messages, files, and other content |
Channels
| Tool | Description |
|---|---|
| Create channel | Create a new public or private channel |
| List channels | List channels in the workspace |
| Archive channel | Archive an existing channel |
| Invite users to channel | Add members to a channel |
| Set channel topic | Update the topic of a channel |
| Rename channel | Change the name of a channel |
Files and reactions
| Tool | Description |
|---|---|
| Upload file | Upload a file to a channel or conversation |
| List files | List files shared in the workspace |
| Download file | Download a file by its ID |
| Add reaction | Add an emoji reaction to a message |
| Remove reaction | Remove an emoji reaction from a message |
| Pin message | Pin a message to a channel |
Triggers
Triggers fire an agent task automatically — in real time, via webhook — when something happens in Slack. Some triggers require a Channel to be specified during setup.| Trigger | When it fires | Config |
|---|---|---|
| New message received | A new message is posted to a channel | Channel required |
| New channel created | A new channel is created in Slack | — |
| Reaction added | A reaction is added to a message | — |
| Reaction removed | A reaction is removed from a message | — |
| New bot message received | A bot posts a message to a channel | Channel required |
| New direct message received | A direct message is sent to a user | — |
| New private channel message | A message is posted in a private channel | Channel ID required |
| New multi-person DM received | A message is posted in a group DM | — |
| Thread reply received | A reply is added to a message thread | Channel required |
Create a task with a Slack trigger
Open any agent, go to the Tasks tab, and add a new task. In the trigger picker, choose Integration → Slack.
Choose which event to watch
Pick one of the nine available events. For channel-based triggers, enter the channel name or ID.
Example use cases
Auto-respond to support questions in a channel
Auto-respond to support questions in a channel
Trigger: New message received (channel: #support)When a new message arrives in #support, an agent reads the question, searches your knowledge base, and posts a helpful reply in the same thread.
Summarize daily channel activity
Summarize daily channel activity
Ask your agent to fetch the last 24 hours of messages from a channel, generate a summary of key discussions and decisions, and post it to #daily-digest.
Notify a channel when a reaction milestone is hit
Notify a channel when a reaction milestone is hit
Trigger: Reaction addedWhen a message receives a specific emoji (e.g., five fire reactions), the agent posts a celebratory message or forwards the content to a highlights channel.
Troubleshooting
The bot can't post to a private channel
The bot can't post to a private channel
The Slack app must be explicitly invited to private channels. Type
/invite @Mantle in the private channel, then
retry.Messages appear as the bot instead of my name
Messages appear as the bot instead of my name
Composio-based Slack integrations post as the connected app. If you need messages to appear as yourself, check that
your OAuth token has the
chat:write user scope rather than only the bot scope.Trigger tasks aren't firing
Trigger tasks aren't firing
- Confirm the task is active (green indicator on the Tasks tab). 2. Check that the correct channel is specified for channel-based triggers. 3. Verify the webhook was authorised — re-authorise if needed from the task settings.
Search returns no results
Search returns no results
Slack search requires the workspace to have messages indexed. Very new workspaces or free-tier workspaces with
limited history may return fewer results. Ensure the connected account has permission to search.
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