Docker-wrapped Slack MCP server exposed as CLI for token-efficient LLM agent interaction
slack-cli-mcp
"We've been using MCP wrong. Loading all tool definitions upfront consumed ~150,000 tokens before any user request." — Anthropic Engineering Blog
A Docker-wrapped Slack MCP server exposed as CLI, achieving 98.7% token reduction for LLM agents.
Quick Start
# 1. Build
./slack-cli-mcp docker build
# 2. Start + Login
./slack-cli-mcp docker start
./slack-cli-mcp docker creds-login
# 3. Use
./slack-cli-mcp list-channels
Why CLI Over MCP?
| Approach | Token Usage | LLM Accuracy | |----------|-------------|--------------| | Traditional MCP | ~150,000 tokens | Degrades with >2-3 servers | | CLI Interface | ~2,000 tokens | Consistent |
Benefits:
- Token efficiency: Only load what you need
- Scriptable: LLMs compose commands, write wrappers
- Composable: Pipes, redirects, standard shell tools
For the full rationale, see MCP Considered Suboptimal — a technical knowledge base with industry analysis and Anthropic engineering evidence.
Architecture
User/Agent → slack-cli-mcp → Docker Container → Slack API
├── slack-mcp-server
└── mcptools
See docs/architecture.md for details.
Documentation
- Tool Reference - Full command documentation
- Architecture - System design
- Design Principles - Why we built it this way
Components
- korotovsky/slack-mcp-server - Slack MCP server
- f/mcptools - MCP-to-CLI bridge
Future Work
See FUTURE_WORK.md for roadmap including:
- Slack server mock for testing
- Network isolation
- Official Slack MCP integration (when available)
Note: Slack is developing an official MCP server. When available, we'll evaluate integration. File an issue if you'd like to help!
Research
This project is informed by:
- MCP Considered Suboptimal - Technical knowledge base on CLI-over-MCP efficiency
- THESIS.md - Core arguments and triadic failure model
- CLI-SDK-over-context-bloat.md - Token reduction patterns
- Anthropic's 98.7% cost reduction
- Linearis: CLI for AI agents
- The Rise of Industrial Software
License
MIT