> ## Documentation Index
> Fetch the complete documentation index at: https://docs.caylex.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Slack

> Seamless messaging and channel management

The Slack MCP Server integrates with Slack workspaces to enable messaging, channel management, and user interaction, enabling AI agents to assist with communication, task automation, and enhanced collaboration.

## Server Details

| Property       | Value                                             |
| -------------- | ------------------------------------------------- |
| **Transport**  | Streamable HTTP                                   |
| **Hosting**    | Remote (externally hosted)                        |
| **Categories** | Productivity & Collaboration, Business Operations |

## Authentication

This server supports the following authentication method:

### Header Authentication

This server authenticates via HTTP headers. During the server onboarding flow, you will be prompted to confirm the required headers. Note that you do not provide the values for the headers during the server on-boarding.
Header values are provided by the users during the [Auth Link](/auth/auth-links) flow.

## Getting Started

<Steps>
  <Step title="Add the server">
    Navigate to the **Server Library** and click on the **New Server** button. Find **Slack** in the Caylex Catalog.
  </Step>

  <Step title="Server Onboarding flow">
    Go through the server onboarding flow.
  </Step>

  <Step title="Use in a project">
    Add the server to a [project](https://app.caylex.dev/projects) by configuring project connections. Its tools are now available to any agents connected to that project.
  </Step>
</Steps>

## Available Tools

This server provides **13** tools:

<AccordionGroup>
  <Accordion title="slack_user_search_messages">
    Search messages in the workspace. Use to find past messages by keyword or phrase. Optionally restrict to channel\_ids. Returns matching messages with context; use sort/sort\_dir and count for relevance and pagination.
  </Accordion>

  <Accordion title="slack_user_list_channels">
    List channels the authenticated user can access. Use to discover public channels, private channels the user is in, DMs, and group DMs. Returns channel IDs and names for posting or reading. Paginate with cursor and limit (max 200).
  </Accordion>

  <Accordion title="slack_user_reply_to_thread">
    Reply to a thread in a channel as the user. Use when responding to a specific message. Provide channel\_id, thread\_ts (from the parent message), and reply text.
  </Accordion>

  <Accordion title="slack_get_thread_replies">
    Get all messages in a thread. Use when you need replies under a message. Parse Slack URLs like [https://workspace.slack.com/archives/C123456/p1234567890123456](https://workspace.slack.com/archives/C123456/p1234567890123456) as channel\_id='C123456', thread\_ts='1234567890.123456'. Returns parent message and replies.
  </Accordion>

  <Accordion title="slack_bot_reply_to_thread">
    Reply to a thread as the bot. Use when the bot should reply in a thread. Provide channel\_id, thread\_ts, and reply text. Requires bot token in request.
  </Accordion>

  <Accordion title="slack_get_channel_history">
    Get recent messages from a Slack channel. Use after you have a channel\_id (e.g. from slack\_user\_list\_channels or a Slack URL). Returns messages with timestamps and thread\_ts for replies.
  </Accordion>

  <Accordion title="slack_user_get_info">
    Get profile and info for a Slack user by user\_id. Use to resolve display names, emails, or check if a user exists before messaging or inviting.
  </Accordion>

  <Accordion title="slack_bot_post_message">
    Post a new message to a Slack channel as the bot. Use when the bot should send a message (not the user). Provide channel\_id and text. Requires bot token in request.
  </Accordion>

  <Accordion title="slack_bot_add_reaction">
    Add an emoji reaction to a message as the bot. Use when the bot should react to a message. Provide channel\_id, message timestamp, and reaction name (e.g. 'thumbsup'). Requires bot token in request.
  </Accordion>

  <Accordion title="slack_user_add_reaction">
    Add an emoji reaction to a message as the user. Use to react to a message (e.g. thumbsup, eyes). Provide channel\_id, message timestamp, and reaction name (without colons, e.g. 'thumbsup').
  </Accordion>

  <Accordion title="slack_user_post_message">
    Post a new message to a Slack channel as the authenticated user. Use when sending a message to a channel. Provide channel\_id (e.g. C123456) and message text.
  </Accordion>

  <Accordion title="slack_invite_users_to_channel">
    Invite one or more users (or bots) to a Slack channel. Provide channel\_id and a list of user IDs. Use when adding people or bots to a channel. Requires invite permission.
  </Accordion>

  <Accordion title="slack_list_users">
    List all users in the Slack workspace. Use to find user IDs for DMs, mentions, or invites. Supports pagination (cursor, limit) and optional team\_id for Enterprise Grid.
  </Accordion>
</AccordionGroup>

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