slack-mcp-server

Web API Reference

The Slack Web Server exposes all MCP tools as REST endpoints, accessible from any browser or HTTP client.

Claude web now supports remote MCP connectors on paid plans, so this Web API mode is best used for:

References:

Starting the Server

cd ~/slack-mcp-server
npm run web
# Or run directly from npm:
npx -y @jtalk22/slack-mcp web

The server will:

  1. Start on port 3000
  2. Serve the web UI at http://localhost:3000
  3. Generate a secure API key (saved to ~/.slack-mcp-api-key)

Create a LaunchAgent to auto-start the web server on login:

cat > ~/Library/LaunchAgents/com.slack-web-api.plist << 'EOF'
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>com.slack-web-api</string>
    <key>ProgramArguments</key>
    <array>
        <string>/opt/homebrew/bin/node</string>
        <string>/Users/YOUR_USERNAME/slack-mcp-server/src/web-server.js</string>
    </array>
    <key>WorkingDirectory</key>
    <string>/Users/YOUR_USERNAME/slack-mcp-server</string>
    <key>RunAtLoad</key>
    <true/>
    <key>KeepAlive</key>
    <true/>
    <key>StandardOutPath</key>
    <string>/tmp/slack-web-api.log</string>
    <key>StandardErrorPath</key>
    <string>/tmp/slack-web-api.error.log</string>
</dict>
</plist>
EOF

# Load it
launchctl load ~/Library/LaunchAgents/com.slack-web-api.plist

Manage the service:

# Check status
launchctl list | grep slack-web-api

# Restart
launchctl kickstart -k gui/$(id -u)/com.slack-web-api

# Stop
launchctl unload ~/Library/LaunchAgents/com.slack-web-api.plist

Authentication

All API requests require the API key in the Authorization header:

Authorization: Bearer <your-api-key>

The server generates a cryptographically secure API key on first run, saved to ~/.slack-mcp-api-key. The key is printed to the console:

Dashboard: http://localhost:3000/?key=smcp_xxxxxxxxxxxx

To use a custom key:

SLACK_API_KEY=your-custom-key npm run web

Endpoints

GET /

Server info and available endpoints (no auth required).

GET /health

Check Slack connection status.

curl -H "Authorization: Bearer $API_KEY" http://localhost:3000/health

Response:

{
  "status": "ok",
  "code": "ok",
  "message": "Slack auth valid",
  "user": "james",
  "team": "Rêvasser"
}

GET /token-status

Read-only token diagnostics (age/health/cache stats). This endpoint does not trigger Chrome extraction.

curl -H "Authorization: Bearer $API_KEY" http://localhost:3000/token-status

POST /refresh

Force token refresh from Chrome.

curl -X POST -H "Authorization: Bearer $API_KEY" http://localhost:3000/refresh

GET /conversations

List conversations (DMs/channels).

Query Parameters: | Param | Default | Description | |——-|———|————-| | types | im,mpim | Conversation types | | limit | 100 | Max results |

Types: im, mpim, public_channel, private_channel

curl -H "Authorization: Bearer $API_KEY" "http://localhost:3000/conversations?types=im"

Response:

{
  "count": 5,
  "conversations": [
    { "id": "D063M4403MW", "name": "Gwen Santos", "type": "dm" }
  ]
}

GET /conversations/:id/history

Get messages from a conversation.

Query Parameters: | Param | Default | Description | |——-|———|————-| | limit | 50 | Messages to fetch | | oldest | - | Unix timestamp start | | latest | - | Unix timestamp end | | resolve_users | true | Convert user IDs to names |

curl -H "Authorization: Bearer $API_KEY" "http://localhost:3000/conversations/D063M4403MW/history?limit=10"

GET /conversations/:id/full

Export full conversation with threads.

Query Parameters: | Param | Default | Description | |——-|———|————-| | max_messages | 2000 | Max messages | | include_threads | true | Fetch replies | | oldest | - | Unix timestamp start | | latest | - | Unix timestamp end | | output_file | - | Save to file path |

curl -H "Authorization: Bearer $API_KEY" "http://localhost:3000/conversations/D063M4403MW/full?max_messages=500"

GET /conversations/:id/thread/:ts

Get thread replies.

curl -H "Authorization: Bearer $API_KEY" "http://localhost:3000/conversations/D063M4403MW/thread/1767368030.607599"

Search messages across workspace.

Query Parameters: | Param | Default | Description | |——-|———|————-| | q | required | Search query | | count | 20 | Max results |

Query Syntax:

curl -H "Authorization: Bearer $API_KEY" "http://localhost:3000/search?q=from:@gwen%20meeting"

POST /messages

Send a message.

Body:

{
  "channel_id": "D063M4403MW",
  "text": "Hello!",
  "thread_ts": "1767368030.607599"  // optional, for replies
}

curl -X POST -H "Authorization: Bearer $API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"channel_id":"D063M4403MW","text":"Hello!"}' \
  http://localhost:3000/messages

GET /users

List all workspace users.

curl -H "Authorization: Bearer $API_KEY" "http://localhost:3000/users?limit=50"

GET /users/:id

Get user details.

curl -H "Authorization: Bearer $API_KEY" http://localhost:3000/users/U05GPEVH7J9

Web UI

Open http://localhost:3000 in your browser for a visual interface.

The UI auto-connects with the default API key:

  1. Select a conversation from the sidebar
  2. View messages, threads, and user info
  3. Search messages across the workspace
  4. Send messages directly from the browser

Using with claude.ai:

  1. Preferred: add a remote MCP connector in Claude settings if you run a remote endpoint.
  2. Fallback: open the web UI alongside claude.ai for local browsing/search.
  3. Copy-paste relevant message content as needed.

Environment Variables

Variable Default Description
PORT 3000 Server port
SLACK_API_KEY (generated) API key for authentication
SLACK_TOKEN - Slack xoxc token
SLACK_COOKIE - Slack xoxd cookie

Security Notes

  1. API Key: Keep it secret. Anyone with the key can access your Slack.
  2. Local Only: By default, only accessible from localhost.
  3. HTTPS: For remote access, put behind a reverse proxy with HTTPS.
  4. Token Storage: Slack tokens are stored in keychain and token file.
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