Slack MCP Server

Slack MCP server that uses User OAuth Token (xoxp-) to send and read messages as yourself.

Depends only on @modelcontextprotocol/sdk — no third-party Slack libraries.

Features

• Channel name resolution: No need to look up IDs — just use #general or dev_team
• User name resolution: <@U123> in messages is automatically resolved to display names
• Thread auto-expansion: Replies are fetched in parallel and displayed inline
• Message links: Each message includes a direct Slack URL
• @mention resolution: @username in posts is automatically converted to <@ID>
• Token persistence: OAuth token is stored in ~/.config/slack-mcp/token.json — authenticate once, use forever

Quick Start (npx)

No git clone needed. Just configure your MCP client:

{
  "mcpServers": {
    "slack": {
      "command": "npx",
      "args": ["-y", "slack-mcp-user"],
      "env": {
        "SLACK_CLIENT_ID": "YOUR_CLIENT_ID",
        "SLACK_CLIENT_SECRET": "YOUR_CLIENT_SECRET"
      }
    }
  }
}

On first launch, a browser window opens for Slack OAuth. After granting access, the token is persisted and subsequent launches require no interaction.

Alternative: Pass token directly

If you already have a User Token (e.g., for non-interactive environments):

{
  "mcpServers": {
    "slack": {
      "command": "npx",
      "args": ["-y", "slack-mcp-user"],
      "env": {
        "SLACK_USER_TOKEN": "xoxp-your-token-here"
      }
    }
  }
}

Token Resolution Order

1. SLACK_USER_TOKEN environment variable (explicit, highest priority)
2. ~/.config/slack-mcp/token.json (persisted from OAuth)
3. .env file in the project directory (local development fallback)
4. None found → OAuth flow is triggered (requires SLACK_CLIENT_ID and SLACK_CLIENT_SECRET)

Slack App Setup

1. Go to https://api.slack.com/apps and click "Create New App"
2. Select "From an app manifest"
3. Choose your workspace
4. Paste the following manifest:

{
  "display_information": {
    "name": "slack-mcp"
  },
  "oauth_config": {
    "redirect_urls": [
      "http://localhost:3000/callback"
    ],
    "scopes": {
      "user": [
        "bookmarks:read",
        "channels:history",
        "channels:read",
        "channels:write",
        "chat:write",
        "dnd:read",
        "emoji:read",
        "files:read",
        "files:write",
        "groups:history",
        "groups:read",
        "groups:write",
        "identify",
        "im:history",
        "im:read",
        "im:write",
        "links:read",
        "lists:read",
        "lists:write",
        "mpim:history",
        "mpim:read",
        "mpim:write",
        "pins:read",
        "pins:write",
        "reactions:read",
        "reactions:write",
        "reminders:read",
        "reminders:write",
        "search:read",
        "stars:read",
        "stars:write",
        "team:read",
        "usergroups:read",
        "users:read",
        "users:read.email",
        "users.profile:read",
        "users.profile:write"
      ]
    }
  },
  "settings": {
    "org_deploy_enabled": false,
    "socket_mode_enabled": false,
    "token_rotation_enabled": false
  }
}

5. After creation, note the Client ID and Client Secret from the Basic Information page

Tools (40+)

Reading

| Tool | Description | |------|-------------| | slack_list_channels | List channels (public/private/DM/group DM) | | slack_get_channel_history | Get channel history (name-based lookup, thread expansion) | | slack_get_channel_info | Channel details (created, purpose, member count) | | slack_get_channel_members | Channel members (username, email, title) | | slack_get_thread | Get thread replies | | slack_get_pins | Pinned messages (with thread expansion) | | slack_get_bookmarks | Channel bookmarks | | slack_get_unread | Unread channel summary | | slack_search_messages | Search messages (Slack search syntax) | | slack_list_files | Search files (by channel/user/type) | | slack_get_reactions | Get reactions on a message |

Writing

| Tool | Description | |------|-------------| | slack_post_message | Post message (as yourself, thread replies supported) | | slack_send_dm | Send DM (username lookup) | | slack_schedule_message | Schedule a message | | slack_list_scheduled_messages | List scheduled messages | | slack_cancel_scheduled_message | Cancel scheduled message | | slack_update_message | Edit a message | | slack_delete_message | Delete a message | | slack_upload_file | Upload a file |

Reactions & Pins

| Tool | Description | |------|-------------| | slack_add_reaction | Add reaction | | slack_remove_reaction | Remove reaction | | slack_add_pin | Pin a message | | slack_remove_pin | Unpin a message |

Users & Groups

| Tool | Description | |------|-------------| | slack_list_users | All workspace users | | slack_get_user_info | User profile details | | slack_find_user | Search users (name/email partial match) | | slack_get_presence | Online status | | slack_get_dnd | DND (Do Not Disturb) status | | slack_list_usergroups | User groups (@team mentions) | | slack_get_usergroup_members | Group members |

Channel Management

| Tool | Description | |------|-------------| | slack_create_channel | Create channel | | slack_invite_to_channel | Invite to channel | | slack_set_topic | Update topic | | slack_archive_channel | Archive channel | | slack_mark_read | Mark as read |

Status, Reminders & More

| Tool | Description | |------|-------------| | slack_set_status | Change your Slack status | | slack_add_reminder | Set a reminder | | slack_list_reminders | List reminders | | slack_list_emoji | Custom emoji list | | slack_list_saved / slack_remove_saved | Saved items | | slack_get_lists / slack_create_list / ... | Slack Lists (TODO) |

MCP Client Examples

Kiro

~/.kiro/settings/mcp.json:

"slack": {
  "command": "npx",
  "args": ["-y", "slack-mcp-user"],
  "env": {
    "SLACK_CLIENT_ID": "YOUR_CLIENT_ID",
    "SLACK_CLIENT_SECRET": "YOUR_CLIENT_SECRET"
  },
  "disabled": false
}

Claude Desktop

claude_desktop_config.json:

{
  "mcpServers": {
    "slack": {
      "command": "npx",
      "args": ["-y", "slack-mcp-user"],
      "env": {
        "SLACK_CLIENT_ID": "YOUR_CLIENT_ID",
        "SLACK_CLIENT_SECRET": "YOUR_CLIENT_SECRET"
      }
    }
  }
}

Troubleshooting

| Symptom | Fix | |---------|-----| | token_revoked | Token expired. Re-run OAuth or set SLACK_USER_TOKEN | | missing_scope | Add required User Token Scopes in api.slack.com, then re-authenticate | | channel_not_found | Check channel ID. Private channels need groups:read scope | | not_in_channel | Ensure you're a member of the channel | | spawn node ENOENT | Use the full path to node (e.g., /opt/homebrew/bin/node) |

Security

• User Token operates with your account's permissions
• Token is stored in ~/.config/slack-mcp/token.json with 600 permissions (owner-only)
• No secrets are hardcoded in the source code
• Client ID/Secret are passed via environment variables

License

MIT