Slack

HTTPv1.0.0Credential RequiredApr 11, 2026

Documentation

Guide

Manage Slack conversations, channels, users, and search workflows through MCP tools.

A Model Context Protocol (MCP) server that exposes Slack's API for messaging, channel operations, workspace discovery, and user-scoped automation.

Overview

The CL Slack MCP Server provides stateless, token-based Slack API access:

Core messaging and thread workflows
Channel and workspace discovery tools
User and file search capabilities

Perfect for:

AI-assisted Slack operations
Workflow automation across channels and users
Building Slack copilots with MCP-compatible clients

Tools

Returns a lightweight readiness response to confirm the MCP server is running.

Inputs:

none

Output:

{
	"status": "ok",
	"server": "CL Slack MCP Server"
}

usage Example:

POST /mcp/cl-slack-mcp/health_check
{}

Posts text and optional Block Kit content to a Slack conversation.

Inputs:

oauth_token (string, required) - Slack OAuth token (xoxb-... or xoxp-...)
channel (string, required) - Channel ID or name
text (string, optional) - Message text
blocks (array, optional) - Block Kit JSON
thread_ts (string, optional) - Parent timestamp for threaded reply
reply_broadcast (boolean, optional) - Broadcast threaded reply to channel

Output:

Reads recent message history with optional time window filtering.

Inputs:

oauth_token (string, required) - Slack OAuth token
channel (string, required) - Channel ID or name
limit (integer, optional) - Number of messages (1-100)
oldest (string, optional) - Lower timestamp bound
latest (string, optional) - Upper timestamp bound

Output:

{
	"ok": true,
	"messages": []

Updates message text or blocks for a specific channel timestamp.

Inputs:

oauth_token (string, required) - Slack OAuth token
channel (string, required) - Channel ID
ts (string, required) - Message timestamp
text (string, optional) - Updated text
blocks (array, optional) - Updated Block Kit payload

Output:

{
	"ok": true,
	"ts": "1712000000.123456"

Deletes a Slack message by channel and timestamp.

Inputs:

oauth_token (string, required) - Slack OAuth token
channel (string, required) - Channel ID
ts (string, required) - Message timestamp

Output:

{
	"ok": true,
	"channel": "C123ABC456",
	"ts": "1712000000.123456"
}

usage Example:

Adds a thread reply and optionally broadcasts it to the parent channel.

Inputs:

oauth_token (string, required) - Slack OAuth token
channel (string, required) - Channel ID
thread_ts (string, required) - Parent message timestamp
text (string, optional) - Reply text
blocks (array, optional) - Block Kit JSON
broadcast (boolean, optional) - Broadcast to channel

Output:

{
	"ok": true

Lists channels with pagination, type filtering, and archived controls.

Inputs:

oauth_token (string, required) - Slack OAuth token
exclude_archived (boolean, optional) - Exclude archived channels
limit (integer, optional) - Page size (1-100)
cursor (string, optional) - Pagination cursor
types (string, optional) - Comma-separated channel types
team_id (string, optional) - Team ID for org-wide apps

Output:

{
	"ok":

Creates a public or private channel, with optional description.

Inputs:

oauth_token (string, required) - Slack OAuth token
name (string, required) - Channel name
is_private (boolean, optional) - Create private channel
description (string, optional) - Channel description

Output:

{
	"ok": true,
	"channel": {
		"id": "C123ABC456",
		"name"

Archives channel when archive=true; unarchives when archive=false.

Inputs:

oauth_token (string, required) - Slack OAuth token
channel (string, required) - Channel ID
archive (boolean, optional) - Archive toggle

Output:

{
	"ok": true
}

usage Example:

Returns channel details including membership counts where available.

Inputs:

oauth_token (string, required) - Slack OAuth token
channel (string, required) - Channel ID

Output:

{
	"ok": true,
	"channel": {
		"id": "C123ABC456"
	}
}

usage Example:

Invites one or more user IDs to the target channel.

Inputs:

oauth_token (string, required) - Slack OAuth token
channel (string, required) - Channel ID
users (array[string], required) - User IDs to invite

Output:

{
	"ok": true,
	"channel": {
		"id": "C123ABC456"
	}
}

usage Example:

Paginates through channel listings and returns a combined map.

Inputs:

oauth_token (string, required) - Slack OAuth token
include_archived (boolean, optional) - Include archived channels

Output:

{
	"ok": true,
	"channels": [],
	"total": 0
}

usage Example:

Performs direct ID lookup and fallback member filtering.

Inputs:

oauth_token (string, required) - Slack OAuth token
query (string, required) - Name, email, or user ID

Output:

{
	"ok": true,
	"matches": [],
	"total": 0
}

usage Example:

Collects root messages that represent thread starters and returns summary fields.

Inputs:

oauth_token (string, required) - Slack OAuth token
channel (string, required) - Channel ID
limit (integer, optional) - Number of messages scanned

Output:

{
	"ok": true,
	"threads": [],
	"note": "For full async summarization, implement polling with job ID"
}

usage Example:

Lists users with pagination controls.

Inputs:

oauth_token (string, required) - Slack OAuth token
limit (integer, optional) - Users per page (1-100)
cursor (string, optional) - Pagination cursor

Output:

{
	"ok": true,
	"members": []
}

usage Example:

Returns workspace details from Slack team.info.

Inputs:

oauth_token (string, required) - Slack OAuth token

Output:

{
	"ok": true,
	"team": {
		"id": "T123ABC456",
		"name": "Workspace Name"
	}
}

usage Example:

Fetches active/away style presence for a given user ID.

Inputs:

oauth_token (string, required) - Slack OAuth token
user (string, required) - Slack user ID

Output:

{
	"ok": true,
	"presence": "active"
}

usage Example:

POST /mcp/cl-slack-mcp/get_user_presence

API Parameters Reference

Channel Resource:

channel ID format: C########
Example: C123ABC456

user Resource:

user ID format: U######## or W########
Example: U123ABC456

message Resource:

message timestamp format: 1712000000.123456
Example:

Authentication Guide

All tools require a valid Slack OAuth token. This server supports user tokens (xoxp-...) and bot tokens (xoxb-...).

Step 1: Create Slack App

Go to Slack App Management
Create a new app from scratch
Select your workspace

Step 2: Configure OAuth Credentials

Open OAuth & Permissions in your app settings
Copy Client ID and Client Secret
Add redirect URL (HTTPS required), for example:
https://your-tunnel-host/slack/oauth/callback

Step 3: Generate Token with Included Script

Use get_slack_oauth_token.py from this repository.

Example user token flow:

Troubleshooting

Missing or Invalid Token

Cause: oauth_token is missing, malformed, expired, or revoked
Solution:
1. Generate a fresh token with get_slack_oauth_token.py
2. Confirm token prefix (xoxp- or xoxb-)
3. Verify token has required scopes

Missing Scope Errors

Cause: Token does not include scope required by the Slack endpoint
Solution:
1. Add needed scope in Slack app dashboard
2. Reinstall/reauthorize app
3. Generate a new token

bad_redirect_uri During OAuth

Cause: Redirect URI mismatch between authorize and token-exchange steps
Solution:
1. Ensure exact same redirect URI is used in both steps
2. Confirm redirect URL is added in Slack app settings
3. Use HTTPS tunnel (zrok/ngrok) and keep it running

App Requests Bot Install Unexpectedly

Resources

Connect

Get connection URL

https://gateway.mewcp.com/slack/mcp

Code Snippets

{
  "inputs": [
    {
      "type": "promptString",
      "id": "slack-api-key",
      "password": true
    }
  ],
  "servers": {
    "slack": {
      "type": "http",
      "url": "https://gateway.mewcp.com/slack/mcp",
      "headers": {
        "Authorization": "Bearer ${input:slack-api-key}"
      }
    }
  }
}

Request Builder

import asyncio
from fastmcp import Client

# Real MewCP gateway URL for this server
GATEWAY_URL = "https://gateway.mewcp.com/slack/mcp"
API_KEY = "YOUR_API_KEY"

headers={
    "Authorization": f"Bearer {API_KEY}"
}

async def main():
    
    client = Client(GATEWAY_URL, headers=headers)
    
    async with client:
        # Test the connection by pinging the server
        await client.ping()
        
        # List available operations
        tools = await client.list_tools()
        resources = await client.list_resources()
        prompts = await client.list_prompts()

        # Execute operations
        result = await client.call_tool("example_tool", {"param": "value"})
        print(result)

asyncio.run(main())

Slack

Documentation

Overview

Tools

API Parameters Reference

Authentication Guide

Step 1: Create Slack App

Step 2: Configure OAuth Credentials

Step 3: Generate Token with Included Script

Troubleshooting

Missing or Invalid Token

Missing Scope Errors

bad_redirect_uri During OAuth

App Requests Bot Install Unexpectedly

Resources

Overview

Tools

API Parameters Reference

Authentication Guide

Step 1: Create Slack App

Step 2: Configure OAuth Credentials

Step 3: Generate Token with Included Script

Troubleshooting

Missing or Invalid Token

Missing Scope Errors

bad_redirect_uri During OAuth

App Requests Bot Install Unexpectedly

Resources

Step 4: Required Scopes

MCP Server Not Reachable