Slack

Overview

Slack is a channel-based messaging platform that connects teams and tools in a single environment. With the Slack integration in SquadOS, your agents can send and read messages, create and archive channels, search conversations, upload files, and manage users — all programmatically, without manual intervention.

• Official website: https://slack.com/
• Composio documentation: docs.composio.dev/toolkits/slack

Authentication

This tool uses OAuth 2.0 (OAUTH2) to connect.

Authentication is managed by Composio via a hosted OAuth flow. You authorize access to your Slack workspace on the Composio secure connection page — no manual API key required.

Field	Required	Description
oauth_token	Yes	OAuth token automatically generated by the Slack authorization flow. Managed by Composio.

How to get credentials

1. Go to Tools in the side menu (/admin/tools), open the Available tab, and click the Slack card.
2. Click Connect — you will be redirected to the Composio secure authorization page.
3. Click Allow to authorize Composio’s access to your Slack workspace.
4. After authorization, you are returned to SquadOS with the Slack account connected.

Tip

To use your own OAuth credentials (custom Slack app), see the How to create OAuth credentials for Slack guide on Composio. This is recommended for workspaces with app approval policies.

How to connect in SquadOS

1. Go to Tools in the side menu (/admin/tools).
2. Open the Available tab and search for Slack.
3. Click the card to open the details modal and hit Connect.
4. You’re taken to the secure connection page hosted by Composio, where you authorize access (OAuth) to your Slack workspace.
5. Once done, you’re sent back to SquadOS with the account connected and the tool available to agents. (Connection-flow details in Organization Tools.)

FAQ

What does the Composio + Slack integration do?

Composio turns Slack’s API into ready-to-use tools that AI agents and automations can call. With the integration you can send and read messages, manage channels, upload files, react to events, search conversations, and more. Composio supports two toolkits: Slack (authenticate as a user for workspace-level actions) and Slackbot (authenticate as a bot for in-channel messaging, app mentions, and slash commands).

Do I have to be a Workspace Owner to install the app?

In some cases — yes. When installing non-Marketplace apps, you’ll need to be an owner to install directly. As a member, you’d need to request approval or ask the owner to disable the approved apps requirement.

Why am I being asked to submit a request during auth?

Because Require approved apps is enabled in the workspace’s App Management Settings. Slack is asking for admin/owner approval before completing the install. See the Composio guide for using your own OAuth credentials as an alternative.

What is the difference between Slack and Slackbot toolkits?

The Slack toolkit provides workspace-level API access (channels, files, users) and can post as the app. The Slackbot toolkit is bot-centric (messaging, interactivity) and posts as the bot user. Slack triggers cover workspace events; Slackbot covers bot entry points like app mentions, DMs, and slash commands.

What does the as_user parameter do in Slack tools?

For the Slack toolkit, set as_user=true to post as the authenticated user. For Slackbot, leave it blank (defaults to false). A missing_charset error usually means invalid as_user, wrong channel ID, or missing required fields.

Available actions

Note

This integration exposes 150 actions in total. The most relevant ones are listed below; see the full list in the Composio documentation.

Send message

SLACK_SEND_MESSAGE

Posts a message to a Slack channel, DM, or private group. Provide exactly one visible content mode: markdown_text for normal Markdown content, or blocks for raw Slack Block Kit layouts. Use fallback_text only with blocks. Not idempotent — duplicate calls post duplicate messages.

Input parameters

Name	Type	Required	Description
channel	string	Yes	ID or name of the channel, private group, or IM channel to send the message to. Do NOT include the ’#’ prefix. For DMs, use the channel ID returned by SLACK_OPEN_DM.
markdown_text	string	No	Use for normal LLM-written message content. Pass standard Markdown; supports headings, bold, italic, links, lists, code, quotes, dividers, and tables.
blocks	array	No	Use only when you need Slack Block Kit capabilities that Markdown cannot express: buttons, select menus, checkboxes, date/time pickers, etc. Do not use together with markdown_text.
thread_ts	string	No	Timestamp (ts) of an existing message to make this a threaded reply.
fallback_text	string	No	Required only when using blocks. Plain text for notifications and clients that cannot render blocks.
unfurl_links	boolean	No	Enable unfurling of text-based URLs.
unfurl_media	boolean	No	Enable media previews from URLs.
reply_broadcast	boolean	No	If true for a threaded reply, also posts to main channel.

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.

Send message (legacy)

SLACK_CHAT_POST_MESSAGE

(DEPRECATED: use SLACK_SEND_MESSAGE) Posts a message to a Slack channel, DM, or private group. Requires at least one content field (markdown_text, text, blocks, or attachments). Body limit ~4000 characters. Rate-limited at ~1 req/sec.

Input parameters

Name	Type	Required	Description
channel	string	Yes	ID or name of the channel, private group, or IM channel.
markdown_text	string	No	PREFERRED: Write your message in markdown for nicely formatted display.
text	string	No	DEPRECATED: This sends raw text only; use the markdown_text field.
blocks	string	No	DEPRECATED: Use markdown_text instead. Block Kit layout blocks as JSON string.
thread_ts	string	No	Timestamp of an existing message for threaded reply.
link_names	boolean	No	Automatically hyperlink channel names and usernames in the text.
unfurl_links	boolean	No	Enable unfurling of URLs.
unfurl_media	boolean	No	Enable media previews.
reply_broadcast	boolean	No	If true for a threaded reply, also posts to main channel.

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.

Schedule message

SLACK_SCHEDULE_MESSAGE

Schedules a message to a Slack channel, DM, or private group for a future time (post_at). Scheduling is limited to 120 days in advance.

Input parameters

Name	Type	Required	Description
channel	string	No	Channel, private group, or DM channel ID (e.g., C1234567890) or name. Bot must be a member of the target channel.
post_at	string	No	Unix EPOCH timestamp (integer seconds since 1970-01-01 00:00:00 UTC) for the future message send time.
markdown_text	string	No	PREFERRED: Write your scheduled message in markdown for nicely formatted display.
text	string	No	Primary text of the message; use markdown_text for formatting.
thread_ts	string	No	Timestamp of the parent message for the scheduled message to be a thread reply.
unfurl_links	boolean	No	Pass false to disable automatic link unfurling.
unfurl_media	boolean	No	Pass false to disable automatic media unfurling.

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.

Send ephemeral message

SLACK_SEND_EPHEMERAL_MESSAGE

Sends an ephemeral message visible only to the specified user in a channel; other channel members cannot see it. Both the bot and the target user must be members of the specified channel.

Input parameters

Name	Type	Required	Description
user	string	Yes	User ID of the user to send the ephemeral message to.
channel	string	Yes	Channel, private group, or DM channel to send message to.
markdown_text	string	No	PREFERRED: Write your ephemeral message in markdown. Maximum 12,000 characters.
text	string	No	The message text to display. Required unless ‘blocks’ or ‘attachments’ is provided.
thread_ts	string	No	Provide another message’s ts value to make this message a reply.

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.

Create channel

SLACK_CREATE_CHANNEL

Initiates a public or private channel-based conversation in a Slack workspace. Immediately creates the channel; invoke only after explicit user confirmation.

Input parameters

Name	Type	Required	Description
name	string	Yes	Name of the public or private channel to create. Must be lowercase, unique, and contain no spaces or periods; max 80 characters.
is_private	boolean	No	Create a private channel instead of a public one.
team_id	string	No	Encoded team id to create the channel in, required if org token is used.

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.

Delete channel

SLACK_DELETE_CHANNEL

Permanently and irreversibly deletes a specified public or private channel, including all its messages and files, within a Slack Enterprise Grid organization.

Input parameters

Name	Type	Required	Description
channel_id	string	Yes	ID of the channel to be permanently deleted.

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.

Archive a Slack conversation

SLACK_ARCHIVE_CONVERSATION

Archives a Slack conversation by its ID, rendering it read-only and hidden while retaining history. Ideal for cleaning up inactive channels; be aware that some channels (like #general or certain DMs) cannot be archived.

Input parameters

Name	Type	Required	Description
channel	string	No	ID of the Slack conversation to archive.

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.

Unarchive channel

SLACK_UNARCHIVE_CHANNEL

Reverses conversation archival.

Input parameters

Name	Type	Required	Description
channel	string	Yes	ID of conversation to unarchive.

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.

Rename a conversation

SLACK_RENAME_CONVERSATION

Renames a Slack channel, automatically adjusting the new name to meet naming conventions (e.g., converting to lowercase), which may affect integrations using the old name.

Input parameters

Name	Type	Required	Description
channel	string	No	ID of the conversation (channel) to rename.
name	string	No	New name for the conversation. Must be 80 characters or less and contain only lowercase letters, numbers, hyphens, and underscores.

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.

List all channels

SLACK_LIST_ALL_CHANNELS

Lists conversations available to the user with various filters and search options. Always use resolved channel_id (not display names) for downstream operations, as names may be non-unique.

Input parameters

Name	Type	Required	Description
limit	integer	No	Maximum number of channels to return per page (1 to 1000).
types	string	No	Comma-separated list of conversation types: public_channel, private_channel, im, mpim. Defaults to public_channel.
cursor	string	No	Pagination cursor (from next_cursor of a previous response).
team_id	string	No	Encoded team id to list channels in. Required with org token.
exclude_archived	boolean	No	Excludes archived channels if true.

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.

List conversations

SLACK_LIST_CONVERSATIONS

Lists conversations (channels/DMs) accessible to a specified user (or the authenticated user if no user ID is provided). Returns conversation IDs (C* for channels, G* for group DMs), not display names.

Input parameters

Name	Type	Required	Description
user	string	No	The ID of the user whose conversations will be listed. If not provided, conversations for the authenticated user are returned.
limit	integer	No	The maximum number of items to return per page.
types	string	No	Comma-separated list of conversation types to include: public_channel, private_channel, im, mpim.
cursor	string	No	Pagination cursor for retrieving the next set of results.
team_id	string	No	The team (workspace) ID to filter conversations by.
exclude_archived	boolean	No	Set to true to exclude archived channels from the list.

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.

Fetch conversation history

SLACK_FETCH_CONVERSATION_HISTORY

Fetches a chronological list of messages and events from a specified Slack conversation. IMPORTANT LIMITATION: This action only returns messages from the main channel timeline. Threaded replies are NOT returned — use SLACK_FETCH_MESSAGE_THREAD_FROM_A_CONVERSATION for that.

Input parameters

Name	Type	Required	Description
channel	string	Yes	The ID of the public channel, private channel, direct message, or multi-person direct message to fetch history from.
limit	integer	No	Maximum number of messages to request in this single Slack API call (1-1000). Defaults to 100.
cursor	string	No	Pagination cursor from response_metadata.next_cursor of a previous response.
oldest	string	No	Start of the time range of messages to include in results. Accepts a Unix timestamp or a Slack timestamp.
latest	string	No	End of the time range of messages to include in results.
inclusive	boolean	No	When true, includes messages at the exact ‘oldest’ or ‘latest’ boundary timestamps in results.
include_all_metadata	boolean	No	Return all metadata associated with messages in the conversation history.

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.

Retrieve conversation replies

SLACK_FETCH_MESSAGE_THREAD_FROM_A_CONVERSATION

Retrieves replies to a specific parent message in a Slack conversation, using the channel ID and the parent message’s timestamp (ts).

Input parameters

Name	Type	Required	Description
channel	string	No	ID of the conversation (channel, direct message, etc.) to fetch the thread from. Must be a channel ID, not a channel name.
ts	string	No	Timestamp of the parent message in the thread. Must be the exact full timestamp string of the root/parent message.
limit	integer	No	Maximum number of messages to return.
cursor	string	No	Pagination cursor from response_metadata.next_cursor of a previous response.
oldest	string	No	Oldest message timestamp in the time range to include results.
latest	string	No	Latest message timestamp in the time range to include results.
inclusive	boolean	No	Whether to include messages with latest or oldest timestamps in results.

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.

Add reaction to message

SLACK_ADD_REACTION_TO_AN_ITEM

Adds a specified emoji reaction to an existing message in a Slack channel, identified by its timestamp; does not remove or retrieve reactions.

Input parameters

Name	Type	Required	Description
name	string	Yes	Name of the emoji to add as a reaction (e.g., ‘thumbsup’). This is the emoji name without colons. For emojis with skin tone modifiers, append ‘::skin-tone-X’ where X is a number from 2 to 6.
channel	string	Yes	ID of the channel where the message to add the reaction to was posted.
timestamp	string	Yes	Timestamp of the message to which the reaction will be added (e.g., ‘1234567890.123456’).

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.

Remove reaction from item

SLACK_REMOVE_REACTION_FROM_ITEM

Removes an emoji reaction from a message, file, or file comment in Slack. Provide exactly one targeting method: channel+timestamp together, file, or file_comment.

Input parameters

Name	Type	Required	Description
name	string	Yes	Name of the emoji reaction to remove (e.g., ‘thumbsup’), without colons.
channel	string	No	Channel ID of the message. Required if timestamp is provided.
timestamp	string	No	Timestamp of the message. Required if channel is provided.
file	string	No	ID of the file to remove the reaction from.
file_comment	string	No	ID of the file comment to remove the reaction from.

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.

Upload or create a file in Slack

SLACK_UPLOAD_OR_CREATE_A_FILE_IN_SLACK

Upload files, images, screenshots, documents, or any media to Slack channels or threads. Supports all file types including images (PNG, JPG, JPEG, GIF), documents (PDF, DOCX, TXT), code files, and more.

Input parameters

Name	Type	Required	Description
file	string	No	File(s) to upload. At least one of ‘content’ or ‘file’ must be provided.
content	string	No	Text content of the file; use for text-based files. At least one of ‘content’ or ‘file’ must be provided.
channels	string	No	Channel ID where the file will be shared. Use channel ID (e.g., C1234567890) not channel name.
title	string	No	Title of the file, displayed in Slack.
filename	string	No	Filename to be displayed in Slack. Required when using ‘content’ parameter.
thread_ts	string	No	Timestamp of a parent message to upload this file as a reply.
initial_comment	string	No	Optional message to introduce the file in specified ‘channels’.

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.

List Slack files

SLACK_LIST_FILES_WITH_FILTERS_IN_SLACK

Lists files and their metadata within a Slack workspace, filterable by user, channel, timestamp, or type; returns metadata only, not file content.

Input parameters

Name	Type	Required	Description
channel	string	No	Filter files appearing in a specific channel, indicated by its Slack Channel ID.
user	string	No	Filter files created by a single user. Provide the Slack User ID.
types	string	No	Filter by file type (comma-separated): all, spaces, snippets, images, pdfs, gdocs, zips. Defaults to ‘all’.
ts_from	integer	No	Filter files created after this Unix timestamp (inclusive).
ts_to	integer	No	Filter files created before this Unix timestamp (inclusive).
count	string	No	Number of files to return per page. Default is 100, maximum is 1000.
page	string	No	Page number of results to retrieve when paginating. Default is 1.
team_id	string	No	The team/workspace ID to list files from. Required for Enterprise Grid workspaces.

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.

List all users

SLACK_LIST_ALL_USERS

Retrieves a paginated list of all users with profile details, status, and team memberships in a Slack workspace. Filter is_bot, is_app_user, and deleted fields to build human-only rosters.

Input parameters

Name	Type	Required	Description
limit	integer	No	Maximum number of items to return per page. Recommended to set a value (e.g., 100).
cursor	string	No	Pagination cursor for fetching subsequent pages.
team_id	string	No	The workspace/team ID to list users from. Required when using an org-level token (Enterprise Grid).
include_locale	boolean	No	Include the locale field for each user. Defaults to false.

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.

Find users

SLACK_FIND_USERS

Find users in a Slack workspace by any criteria — email, name, display name, or other text. Includes optimized email lookup for exact email matches.

Input parameters

Name	Type	Required	Description
search_query	string	No	Search query to find users. Can be a Slack user ID, email address, or name. Required if email is not provided.
email	string	No	Email address to search for. Convenience parameter for email-based search.
limit	integer	No	Maximum number of users to return (1 to 1000). Defaults to 50.
exact_match	boolean	No	When true, only returns users with exact matches (case-insensitive).
include_bots	boolean	No	Include bot users in search results. Defaults to false.
team_id	string	No	The ID of the Slack workspace. Required when using an org-level token.
include_deleted	boolean	No	Include deleted/deactivated users in search results. Defaults to false.

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.

Lookup users by email

SLACK_FIND_USER_BY_EMAIL_ADDRESS

Retrieves the Slack user object for an active user by their registered email address; requires the users:read.email OAuth scope. Fails with ‘users_not_found’ if the email is unregistered or the user is inactive.

Input parameters

Name	Type	Required	Description
email	string	Yes	The email address of the user to look up.

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.

Invite users to a Slack channel

SLACK_INVITE_USERS_TO_A_SLACK_CHANNEL

Invites users to an existing Slack channel using their valid Slack User IDs. Response is always HTTP 200; inspect ok, error, and errors fields to confirm users were added.

Input parameters

Name	Type	Required	Description
channel	string	No	ID of the public or private Slack channel to invite users to; must be an existing channel.
users	string	No	Comma-separated string of valid Slack User IDs to invite. Up to 1000 user IDs can be included.
force	boolean	No	When set to true and multiple user IDs are provided, continue inviting the valid ones while disregarding invalid IDs.

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.

Remove user from conversation

SLACK_REMOVE_USER_FROM_CONVERSATION

Removes a specified user from a Slack conversation (channel); the caller must have permissions to remove users and cannot remove themselves using this action.

Input parameters

Name	Type	Required	Description
channel	string	No	ID of the conversation (channel) to remove the user from.
user	string	No	The ID of the user to be removed from the conversation.

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.

Update a Slack message

SLACK_UPDATES_A_SLACK_MESSAGE

Updates a Slack message by timestamp. Provide exactly one visible content mode: markdown_text for normal Markdown content, or blocks for raw Slack Block Kit layouts.

Input parameters

Name	Type	Required	Description
ts	string	Yes	Timestamp of the message to update (e.g., '1234567890.123456').
channel	string	Yes	ID or name of the channel containing the message to update. Do NOT include the ’#’ prefix.
markdown_text	string	No	Use for normal LLM-written updated message content. Supports standard Markdown.
blocks	array	No	Use when you need Slack Block Kit capabilities. Do not use together with markdown_text.
fallback_text	string	No	Required only when using blocks. Plain text for notifications.
as_user	boolean	No	Pass true to update the message as the authenticated user.
reply_broadcast	boolean	No	If true and the message is a thread reply, broadcast the updated message to the channel.

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.

Delete a message from a chat

SLACK_DELETES_A_MESSAGE_FROM_A_CHAT

Deletes a message, identified by its channel ID and timestamp, from a Slack channel, private group, or direct message conversation; the authenticated user or bot must be the original poster.

Input parameters

Name	Type	Required	Description
channel	string	No	The ID of the channel, private group, or direct message conversation containing the message to be deleted.
ts	string	No	Timestamp of the message to be deleted. Must be the exact Slack message timestamp string with fractional precision (e.g., ‘1234567890.123456’).
as_user	boolean	No	Legacy parameter. Pass true to delete the message as the authed user.

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.

Search messages

SLACK_SEARCH_MESSAGES

Workspace-wide Slack message search with date ranges and filters. Use query modifiers (e.g., in:#channel, from:@user, before/after:YYYY-MM-DD), sorting (score/timestamp), and pagination.

Input parameters

Name	Type	Required	Description
query	string	Yes	Search query supporting various modifiers: in:#channel-name, from:@username, "exact phrase", before:YYYY-MM-DD, after:YYYY-MM-DD, has:link, has:file.
sort	string	No	Sort results by score (relevance) or timestamp (chronological).
sort_dir	string	No	Sort direction: asc (ascending) or desc (descending).
count	integer	No	Number of messages per page (max 100). With auto_paginate, total messages desired.
page	integer	No	Page number for manual pagination control.
cursor	string	No	Cursor for cursor-mark pagination. Use * for the first call.
highlight	boolean	No	Enable highlighting of search terms in results.
auto_paginate	boolean	No	When enabled, count becomes the total messages desired and the system handles pagination automatically.
team_id	string	No	The ID of the workspace to search in. Only relevant when using an org-level token.

Output

Name	Type	Required	Description
data	string	Yes	Data from the action execution.
error	string	No	Error message if the execution failed.
successful	boolean	Yes	Whether the action execution was successful.