Slack Channel MCP Server

An MCP (Model Context Protocol) server that enables Slackbot to create Slack channels through natural language conversation.

Overview

This server exposes a single tool create_slack_channel that allows you to create Slack channels by talking to Slackbot. It uses the Slack API's conversations.create method.

Architecture:

User → Slackbot (Slack's AI) → MCP Server (HTTP) → Slack API

Related MCP server: Slack MCP Server

Quick Start

1. Prerequisites

• Node.js 18+ - For running the server

• npm - For dependency management

• ngrok - For exposing localhost to the internet (for local development)

• Slack workspace - Where you want to create channels

• Slack app credentials - Bot token with appropriate scopes

2. Install Dependencies

cd /Users/asalinerojeffrey/Projects/slack-channel-mcp-server
npm install

3. Get Your Slack Bot Token

1. Go to https://api.slack.com/apps

2. Click "Create New App" → "From scratch"

3. App name: Channel Creator MCP

4. Select your workspace

5. Go to "OAuth & Permissions" in the left sidebar

6. Under "Scopes", add these Bot Token Scopes:

   • mcp:connect (required for MCP)

   • channels:manage (to create public channels)

   • groups:write (to create private channels)

7. Click "Install to Workspace" at the top

8. Copy the Bot User OAuth Token (starts with xoxb-)

9. Save it to your .env file

4. Configure Environment

# Copy the example file
cp .env.example .env

# Edit .env and add your bot token
# SLACK_BOT_TOKEN=xoxb-your-token-here

5. Start the Server Locally

npm run dev

You should see:

🚀 Slack Channel MCP Server running on http://localhost:3000
   MCP endpoint: http://localhost:3000/mcp
   Health check: http://localhost:3000/health

6. Expose with ngrok (New Terminal)

# Install ngrok if needed
brew install ngrok

# Start ngrok
ngrok http 3000

You'll see something like:

Forwarding                    https://1a2b3c4d.ngrok.io -> http://localhost:3000

Copy the HTTPS URL (e.g., https://1a2b3c4d.ngrok.io) - you'll need this next.

7. Configure Slack App for MCP

1. Go back to https://api.slack.com/apps → Your app

2. In the left sidebar under "Features", click "MCP Servers"

3. Click "Add MCP Server"

4. Fill in:

   • Display name: Channel Creator

   • HTTPS endpoint URL: Paste your ngrok URL + /mcp (e.g., https://1a2b3c4d.ngrok.io/mcp)

   • Authentication method: No Auth (for demo)

5. Click "Save"

6. Server should show as "Connected" ✅

8. Test with Slackbot

1. Open your Slack workspace

2. Find Slackbot in Direct Messages or @mention it in a channel

3. Try asking:

   • "Create a channel called test-demo"

   • "Make a private channel for our team"

   • "Set up a new channel named project-alpha"

4. Slackbot will:

   • Recognize your intent

   • Offer the create_slack_channel tool

   • Ask you to authorize it (first time only)

   • Execute the tool and confirm

Testing Before Slackbot

Test with MCP Inspector

The MCP Inspector is a UI tool to test MCP servers locally:

# Terminal 3: Start MCP Inspector
npx @modelcontextprotocol/inspector

1. Select "Streamable HTTP" from the dropdown

2. Enter the URL: http://localhost:3000/mcp

3. Click "Connect"

4. You'll see the create_slack_channel tool

5. Test it by entering:

   • name: mcp-test-123

   • is_private: false

6. Click "Call Tool"

7. Check your Slack workspace - the channel should appear!

Test with curl

curl -X POST http://localhost:3000/mcp \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "id": 1,
    "method": "tools/list"
  }'

Should return JSON with tool definitions.

Test the tool directly

curl -X POST http://localhost:3000/mcp \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "id": 1,
    "method": "tools/call",
    "params": {
      "name": "create_slack_channel",
      "arguments": {
        "name": "curl-test-channel",
        "is_private": false
      }
    }
  }'

Tool Reference

create_slack_channel

Creates a new Slack channel.

Parameters:

Example:

{
  "name": "project-alpha",
  "is_private": false,
  "description": "Planning and development for Project Alpha"
}

Response on Success:

{
  "success": true,
  "message": "Channel created successfully",
  "channel": {
    "id": "C12345678",
    "name": "project-alpha",
    "is_private": false,
    "created": 1704067200,
    "url": "https://slack.com/app_redirect?channel=C12345678"
  }
}

Response on Error:

{
  "success": false,
  "error": "Channel name \"my-channel\" is already taken. Please choose a different name."
}

Common Errors & Solutions

"Unexpected error" in Slack

1. Check if ngrok is running:

   curl https://<your-ngrok-url>/health

2. Verify server is accessible:

   curl https://<your-ngrok-url>/mcp -X POST

3. Check Slack app MCP configuration has correct URL (with /mcp at the end)

Tool doesn't appear in Slackbot

1. Verify MCP server is "Connected" in Slack app settings

2. Test with MCP Inspector: Is the tool listed?

3. Restart Slack client

4. Try a fresh conversation with Slackbot

"name_taken" error

Channel name already exists. Try a different name or check existing channels in Slack.

"missing_scope" error

Your Slack app is missing required permissions:

1. Go to OAuth & Permissions in your Slack app

2. Verify you have these scopes:

   • mcp:connect

   • channels:manage

   • groups:write

3. If missing, add them and reinstall the app to your workspace

"not_authed" error

Bot token is invalid or expired:

1. Generate a new token at https://api.slack.com/apps → Your app → OAuth & Permissions

2. Update .env with the new token

3. Restart the server

60 second timeout

Tool took too long to respond. This could be:

• Network latency to Slack API

• Slack API rate limiting

• Invalid token causing retry logic

Try again or check your Slack app's token permissions.

Troubleshooting

Server won't start

# Check if port 3000 is in use
lsof -i :3000

# Use a different port
PORT=3001 npm run dev

ngrok URL expires

Free ngrok URLs change every time you restart ngrok:

1. Get the new URL

2. Update Slack app MCP server configuration

3. No need to restart anything else

For permanent URLs: Upgrade to paid ngrok or deploy to a cloud provider.

Bot missing permissions

Solution: Reinstall the app after adding scopes:

1. Go to https://api.slack.com/apps → Your app

2. Click "Install to Workspace"

3. Re-authorize the app

4. Copy the new token to .env

5. Restart server

Production Deployment

To deploy beyond local testing, see Deployment Options in the plan file.

Option 1: Render (Recommended for simplicity)

1. Push code to GitHub

2. Connect to Render.com

3. Create new Web Service

4. Set environment variable SLACK_BOT_TOKEN

5. Deploy

6. Use Render URL (https://...) in Slack app MCP configuration

Option 2: Railway

Similar to Render, supports Node.js deployments with free tier.

Option 3: Fly.io

Offers generous free tier and quick deployment.

Option 4: Cloudflare Workers

For serverless deployment with minimal cost.

Security Notes

⚠️ For demo/development only:

• Using "No Auth" authentication mode

• Bot token in environment variable

🔒 For production:

• Implement request signature verification

• Use "Slack Identity" authentication to receive user context

• Verify _meta.slack request signature before trusting

• Add request logging and monitoring

• Rate limit tool calls

• Deploy on HTTPS only

Development

Build for production

npm run build
npm start

Project structure

src/
├── server.ts          # Main MCP server implementation
package.json           # Dependencies
tsconfig.json          # TypeScript config
.env.example           # Environment template
README.md              # This file

API Reference

See the Slack conversations.create API documentation

MCP Specification

Learn more about the Model Context Protocol:

• MCP Specification

• MCP Servers

Support

For issues:

1. Check this README's troubleshooting section

2. Test with MCP Inspector

3. Verify your Slack app token and scopes

4. Check server logs for error details

License

MIT