Slack MCP Server - Complete Implementation

What is Slack MCP Server - Complete Implementation?

Slack MCP Server is a FastMCP v2 implementation that integrates with the Slack API. It implements 16 features: 4 required (send message, list channels, get channel history, send DM), 4 optional (list users, search messages, upload file, add reaction), 4 bonus Pomodoro timer features, and 4 utilities. It supports full UTF-8 Korean, dual token system, smart file upload, and async asyncio processing.

How to use Slack MCP Server - Complete Implementation?

Install via uv package manager: clone the repo, run uv venv and uv sync, then create a .env file with SLACK_BOT_TOKEN (required) and optionally SLACK_USER_TOKEN and SLACK_TEST_CHANNEL_ID. Configure a Slack app with required Bot Token scopes (e.g. channels:read, chat:write) and optional User Token scopes. Start the server with python slack_mcp_server.py or uv run slack_mcp_server.py. Invoke tools (e.g. send_slack_message) through any MCP host such as Claude.

Key features of Slack MCP Server - Complete Implementation

• Full UTF‑8 Korean support in all messages
• Dual token system: Bot Token + User Token for all features
• Smart file upload with size‑based optimization
• Pomodoro timer with automatic notifications
• Async high‑performance asyncio implementation
• Detailed error handling for all API calls

Use cases of Slack MCP Server - Complete Implementation

• Send messages to channels or DMs with thread replies
• List public/private channels with membership and archive status
• Search messages across the workspace (requires User Token)
• Upload files with automatic method selection based on file size
• Manage Pomodoro timers: start, cancel, list, and check status

FAQ from Slack MCP Server - Complete Implementation

What tokens are required?

A Bot Token (xoxb‑) is required for basic operations (message sending, channel listing, etc.). A User Token (xoxp‑) is optional but needed for search and large file uploads (>100 MB).

What are the file upload limits?

Free plan: 5 GB workspace storage. Individual files up to 1 GB (paid plan). Bot Token can upload up to 100 MB; User Token up to 1 GB.

What Slack API rate limits apply?

Rate limits vary by method tier: Tier 1 = 1+ per minute, Tier 2 = 20+ per minute, Tier 3 = 50+ per minute, Tier 4 = 100+ per minute.

What scopes must the Slack app have?

Bot Token scopes: channels:read, channels:history, chat:write, im:read, im:write, im:history, users:read, reactions:write. User Token scopes: search:read, files:write.

How does the smart file upload work?

Small text files (<50 KB) are sent directly as message content; medium files (50 KB–1 MB) as code snippets; standard files (1 MB–100 MB) via standard upload; large files (100 MB–1 GB) require User Token; extremely large files (>1 GB) only share file info.