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nomos-slack-mcp: Instructions file for Claude Code

CLAUDE.md

nomos-slack-mcp CLAUDE.md is an instructions file for Claude Code from project-nomos/nomos-slack-mcp. It costs 897 tokens per session, scanned A, original, MIT.

A set of instructions for working on nomos-slack-mcp, an MCP server that lets AI agents act in Slack as the user. MCP, or Model Context Protocol, is a way for an AI agent to call external tools; these instructions also cover commands, architecture, and design decisions.

In plain words
What is it for?
Use it when developing, testing, linting, formatting, or configuring the nomos-slack-mcp TypeScript project.
Why use it?
It tells coding agents how this Slack integration is organized and which checks to run before changes are committed. It also explains the authentication model and support for multiple Slack workspaces.

Instructions file for Claude Code

Written for Claude Code: the file is CLAUDE.md. Also seen: mentions CLAUDE.md; mentions Claude Code.

This is project-nomos/nomos-slack-mcp's own configuration. It tells Claude Code how to work on nomos-slack-mcp itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything nomos-slack-mcp configures →

not rated 1repo 5mo ago A scan 897 tokens original MIT
View source ↗ project-nomos/nomos-slack-mcp projectnomos.dev
Reuse

Borrowing it

Nothing to install: this file belongs to project-nomos/nomos-slack-mcp. 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/project-nomos/nomos-slack-mcp/main/CLAUDE.md
Clone the repo
git clone --depth 1 https://github.com/project-nomos/nomos-slack-mcp

Made for: Claude Code.

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README.md
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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.

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Per session 897 This file is loaded in full into every session.
When invoked 897 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00897 $0.00897
Opus 5 $0.00449 $0.00449
Sonnet 5 $0.00179 $0.00179
Haiku 4.5 $0.00090 $0.00090

Measured 8d ago against content hash 7ac37d155c72, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

nomos-slack-mcp 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 8d 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 · 60 lines

How it starts

The opening of the file, as written. The whole thing — 60 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

nomos-slack-mcp is an MCP (Model Context Protocol) server that lets AI agents interact with Slack as the user (not as a bot). It uses user tokens (xoxp-) so messages, reactions, and status updates appear exactly as if typed by the user. Supports multiple Slack workspaces with independent authentication.

Commands

pnpm build            # Compile TypeScript → dist/
pnpm dev              # TypeScript watch mode
pnpm start            # Run compiled server: node dist/src/index.js
pnpm check            # Type-check without emitting (tsc --noEmit)
pnpm lint             # ESLint src/ scripts/
pnpm lint:fix         # ESLint with --fix
pnpm format           # Prettier write all files
pnpm format:check     # Prettier check only
pnpm validate         # check + lint + format:check (run before committing)
pnpm add-workspace    # Interactive CLI to add a Slack workspace (OAuth or manual token)

Pre-commit hooks (husky + lint-staged) auto-fix lint and format on staged .ts, .js, .json, .yml, .yaml, .md files.

Architecture

Transport: stdio (stdin/stdout) — no network listener for MCP communication.

Key layers:

  • src/index.ts — MCP server entry point. Initializes config, client manager, registers tools, connects stdio transport.
  • src/config/config-manager.ts — Reads/writes workspace config from ~/.nomos/slack/config.json (0600 permissions). Validates xoxp- tokens only.
  • src/slack/client-manager.ts — Manages per-workspace WebClient instances. Caches channel and user maps with 5-minute TTL. Resolves #channel-name, @username, or raw IDs to Slack channel IDs.
  • src/slack/formatters.ts — Converts Slack API responses to LLM-friendly text (timestamps, user mention resolution, attachments).
  • src/oauth/ — OAuth 2.0 flow with temporary local HTTPS server (self-signed cert) on localhost:8934 for callback. CSRF via state parameter.
  • src/tools/ — 10 MCP tools (list-workspaces, list-channels, read-messages, read-thread, send-message, reply-thread, search, list-users, set-status, react). Each exports a schema and execute function.
  • scripts/add-workspace.ts — CLI for workspace setup (OAuth or manual token entry), validates via auth.test API.

Read the full file on GitHub · 60 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.

  1. 8d ago First seen · 60 lines · 897 tokens per session scan A 7ac37d155c72

Subscribe to this mod's changes

nomos-slack-mcp CLAUDE.md is an instructions file published in the GitHub repository project-nomos/nomos-slack-mcp (1 stars, last pushed 5mo ago), licensed MIT. It adds 897 tokens to every session, about $0.0045 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 2026-08-31.

Claude Codeagentic-aimcpnomosslackslack-api
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