What is slack-mcp-server CLAUDE.md?

A set of project instructions for a TypeScript server that gives AI assistants access to Slack, a team messaging service. It describes the project, its development commands, and its code-quality checks.

Use it when developing the Slack server to understand its structure, run development and production builds, start examples, and check or fix code quality.

It gives an AI coding assistant the context needed to work on the repository consistently. It also records the commands used to build, run, test, and format the code.

How ubie-oss/slack-mcp-server configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to ubie-oss/slack-mcp-server. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/ubie-oss/slack-mcp-server/main/CLAUDE.md

Clone the repo

git clone --depth 1 https://github.com/ubie-oss/slack-mcp-server

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/ubie-oss/slack-mcp-server/claude-md/github.svg)](https://agentmods.dev/instructions/ubie-oss/slack-mcp-server/claude-md)

Your own site

<a href="https://agentmods.dev/instructions/ubie-oss/slack-mcp-server/claude-md"><img src="https://agentmods.dev/badge/instructions/ubie-oss/slack-mcp-server/claude-md/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/ubie-oss/slack-mcp-server/claude-md"><img src="https://agentmods.dev/badge/instructions/ubie-oss/slack-mcp-server/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 1,149 This file is loaded in full into every session.

When invoked 1,149 The same file — it is already loaded in full.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.01149	$0.01149
Opus 5	$0.00575	$0.00575
Sonnet 5	$0.00230	$0.00230
Haiku 4.5	$0.00115	$0.00115

Measured 9d ago against content hash 891a44205ef2, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

slack-mcp-server CLAUDE.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

CLAUDE.md · 108 lines

How it starts

The opening of the file, as written. The whole thing — 108 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

This is a Model Context Protocol (MCP) server that provides AI assistants with standardized access to Slack APIs. It's written in TypeScript and supports both stdio (process-based) and HTTP transport methods.

Development Commands

Building and Running

npm run build - Compile TypeScript to JavaScript in /dist
npm run dev - Start server in development mode with hot reloading
npm start - Run the production build

Code Quality

npm run lint - Run both ESLint and Prettier checks
npm run fix - Auto-fix all linting issues
npm run lint:eslint - Run ESLint only
npm run lint:prettier - Run Prettier only

Examples

npm run examples - Run stdio transport example
npm run examples:http - Run HTTP transport example

Architecture

Core Structure

The server follows a schema-driven design pattern:

Request/Response Schemas (src/schemas.ts):
- All Slack API interactions are validated with Zod schemas
- Request schemas define input parameters
- Response schemas filter API responses to only necessary fields
Main Server (src/index.ts):
- Dual transport support via command-line flag
- Tool registration and request handling
- Environment variable validation

Transport Modes

Stdio (default): For CLI integration (Claude Desktop, etc.)
HTTP: For web applications via -port flag

Available Tools

All tools follow the pattern: validate request → call Slack API → parse response → return JSON

Channel operations: list, post message, get history
Thread operations: reply, get replies
User operations: get users, profiles, bulk profiles
Message operations: search, add reactions

Tool Selection Guidelines

When to use slack_search_messages:

You need to find messages with specific criteria (keywords, user, date range, channel)
You want to filter/narrow down results based on conditions
You're looking for targeted information rather than browsing

Read the full file on GitHub · 108 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

9d ago First seen · 108 lines · 1,149 tokens per session scan A 891a44205ef2

Subscribe to this mod's changes

slack-mcp-server CLAUDE.md is an instructions file published in the GitHub repository ubie-oss/slack-mcp-server (110 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 1,149 tokens to every session, about $0.0057 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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slack-mcp-server: Instructions file for Claude Code