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Slack MCP Server

Send messages and interact with Slack workspaces.

Overview​

PropertyValue
Package@modelcontextprotocol/server-slack
SourceGitHub
Transportstdio

Installation​

npx -y @modelcontextprotocol/server-slack

Configuration​

mcp_servers:
  - name: slack
    command: npx
    args: ["-y", "@modelcontextprotocol/server-slack"]
    env:
      SLACK_BOT_TOKEN: ${SLACK_BOT_TOKEN}
      SLACK_TEAM_ID: ${SLACK_TEAM_ID}

Required Environment Variables​

  • SLACK_BOT_TOKEN: Bot User OAuth Token (starts with xoxb-)
  • SLACK_TEAM_ID: Your Slack workspace ID

Bot Token Scopes​

Your Slack app needs these OAuth scopes:

  • channels:history - View messages in public channels
  • channels:read - View basic channel info
  • chat:write - Send messages
  • reactions:write - Add reactions
  • users:read - View users

Tools​

slack_list_channels​

List all channels in the workspace.

Parameters: None

Returns: Array of channel objects with id, name, and topic

slack_post_message​

Post a message to a channel.

Parameters:

  • channel_id (string, required): Channel ID
  • text (string, required): Message text

Example:

{
  "tool": "slack_post_message",
  "arguments": {
    "channel_id": "C01234ABCDE",
    "text": "Deployment completed successfully! :rocket:"
  }
}

slack_reply_to_thread​

Reply to a thread.

Parameters:

  • channel_id (string, required): Channel ID
  • thread_ts (string, required): Thread timestamp
  • text (string, required): Reply text

slack_add_reaction​

Add a reaction to a message.

Parameters:

  • channel_id (string, required): Channel ID
  • timestamp (string, required): Message timestamp
  • reaction (string, required): Emoji name (without colons)

Example:

{
  "tool": "slack_add_reaction",
  "arguments": {
    "channel_id": "C01234ABCDE",
    "timestamp": "1234567890.123456",
    "reaction": "white_check_mark"
  }
}

slack_get_channel_history​

Get recent messages from a channel.

Parameters:

  • channel_id (string, required): Channel ID
  • limit (number, optional): Number of messages (default: 10)

slack_get_thread_replies​

Get replies to a thread.

Parameters:

  • channel_id (string, required): Channel ID
  • thread_ts (string, required): Thread timestamp

slack_get_users​

List users in the workspace.

Parameters: None

Returns: Array of user objects

slack_get_user_profile​

Get a user's profile.

Parameters:

  • user_id (string, required): User ID

Use Cases​

Alert Notifier Agent​

apiVersion: aof.sh/v1alpha1
kind: Agent
metadata:
  name: alert-notifier
spec:
  model: google:gemini-2.5-flash
  mcp_servers:
    - name: slack
      command: npx
      args: ["-y", "@modelcontextprotocol/server-slack"]
      env:
        SLACK_BOT_TOKEN: ${SLACK_BOT_TOKEN}
        SLACK_TEAM_ID: ${SLACK_TEAM_ID}
  system_prompt: |
    You send alert notifications to Slack:
    1. Format alerts clearly with severity indicators
    2. Use appropriate emojis for alert types
    3. Include actionable information
    4. Thread follow-up messages

Incident Coordinator​

apiVersion: aof.sh/v1alpha1
kind: Agent
metadata:
  name: incident-coordinator
spec:
  model: google:gemini-2.5-flash
  mcp_servers:
    - name: slack
      command: npx
      args: ["-y", "@modelcontextprotocol/server-slack"]
      env:
        SLACK_BOT_TOKEN: ${SLACK_BOT_TOKEN}
        SLACK_TEAM_ID: ${SLACK_TEAM_ID}
  system_prompt: |
    You coordinate incidents via Slack:
    - Create incident threads
    - Post status updates
    - Tag relevant team members
    - Track resolution progress
    - Post postmortem summaries

Deployment Announcer​

apiVersion: aof.sh/v1alpha1
kind: Agent
metadata:
  name: deploy-announcer
spec:
  model: google:gemini-2.5-flash
  mcp_servers:
    - name: slack
      command: npx
      args: ["-y", "@modelcontextprotocol/server-slack"]
      env:
        SLACK_BOT_TOKEN: ${SLACK_BOT_TOKEN}
        SLACK_TEAM_ID: ${SLACK_TEAM_ID}
  system_prompt: |
    You announce deployments to Slack:
    - Pre-deployment notifications
    - Progress updates
    - Success/failure notifications
    - Rollback alerts

    Format messages with:
    - Environment name
    - Version being deployed
    - Expected duration
    - Rollback plan

Message Formatting​

Basic Formatting​

*bold* _italic_ ~strikethrough~ `code`

Code Blocks​

```python
print("Hello, World!")
```
<https://example.com|Link Text>

User Mentions​

<@U01234ABCDE> mentioned you
Check <#C01234ABCDE|channel-name>

Creating a Slack App​

  1. Go to https://api.slack.com/apps
  2. Click "Create New App"
  3. Choose "From scratch"
  4. Name your app and select workspace
  5. Go to "OAuth & Permissions"
  6. Add required Bot Token Scopes
  7. Install app to workspace
  8. Copy Bot User OAuth Token

Rate Limits​

Slack API has rate limits:

  • Tier 1: 1+ per minute (basic reads)
  • Tier 2: 20+ per minute (common operations)
  • Tier 3: 50+ per minute (posting messages)
  • Tier 4: 100+ per minute (high-volume)

The server handles rate limiting with automatic retries.

Troubleshooting​

Invalid Token​

Verify your token is correct:

curl -H "Authorization: Bearer $SLACK_BOT_TOKEN" \
  https://slack.com/api/auth.test

Missing Scopes​

Check app permissions at: https://api.slack.com/apps/YOUR_APP_ID/oauth

Channel Not Found​

Ensure the bot is invited to the channel:

/invite @your-bot-name

Rate Limited​

Wait for the retry-after period or reduce request frequency.