Borrowing it
Nothing to install: this file belongs to alexmmatos/arthur-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.
curl -O https://raw.githubusercontent.com/alexmmatos/arthur-mcp/main/CLAUDE.mdgit clone --depth 1 https://github.com/alexmmatos/arthur-mcpWrote 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.
[](https://agentmods.dev/instructions/alexmmatos/arthur-mcp/claude-md)<a href="https://agentmods.dev/instructions/alexmmatos/arthur-mcp/claude-md"><img src="https://agentmods.dev/badge/instructions/alexmmatos/arthur-mcp/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.
<a href="https://agentmods.dev/instructions/alexmmatos/arthur-mcp/claude-md"><img src="https://agentmods.dev/badge/instructions/alexmmatos/arthur-mcp/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00674 | $0.00674 |
| Opus 5 | $0.00337 | $0.00337 |
| Sonnet 5 | $0.00135 | $0.00135 |
| Haiku 4.5 | $0.00067 | $0.00067 |
Grade A, and why
arthur-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 6d 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.
How it starts
The opening of the file, as written. The whole thing — 41 lines — stays where its author put it; the contents beside it link to each section on GitHub.
CLAUDE.md
Full shared project memory (protocol, documentation gate, specialist index) lives in AGENTS.md — read it at session start:
@AGENTS.md
Quick reference
Arthur MCP — self-hostable control plane for building/operating MCP servers from APIs, databases, prompts, resources, and internal tools.
- Monorepo: repo root = React 18 + Vite + TypeScript frontend;
api/= NestJS backend. - Persistence: SQLite by default, MongoDB optional via
DATABASEenv var (repository pattern with injection tokens). - Backend domains:
api/src/dynamic-mcp/(MCP tool generation/execution),api/src/swagger/(OpenAPI/Postman import),api/src/auth/,api/src/prompts/,api/src/secrets/,api/src/settings/,api/src/users/,api/src/roles/,api/src/observability/. - Frontend:
src/pages/,src/components/,src/context/,src/i18n.ts+src/locales/,src/theme/.
Commands
| Task | Command |
|---|---|
| Install deps (frontend/backend) | npm install / npm install --prefix api |
| Dev (both) | npm run dev |
| Dev frontend / backend only | npm run start / npm run start:dev --prefix api |
| Build frontend / backend | npm run build / npm run build --prefix api |
| Type-check frontend | npm run type-check |
| Test frontend | npm test |
| Test backend / e2e | npm test --prefix api / npm run test:e2e --prefix api |
| Backend coverage gate | npm run test:cov --prefix api -- --runInBand |
There is no lint script configured (eslint is a devDependency but no eslint.config.*/lint script exists yet); Prettier formatting is defined in .prettierrc.
Topic-scoped conventions
Backend, frontend, and permission-gate conventions are split into .claude/rules/ (auto-loaded only for matching paths) instead of duplicated here — see .claude/rules/backend.md, .claude/rules/frontend.md, and .claude/rules/permissions.md.
Non-negotiables (always apply)
- Database schema/data-shape changes go through migrations — never
synchronize, manual DB edits, or implicit startup sync. - Every new page, tab, API endpoint, integration, credential surface, or settings panel must make an explicit permission decision (reuse or add end-to-end) — see
.claude/rules/permissions.md. - Documentation is part of the deliverable: update
AGENTS.md,docs/ROADMAP.md,docs/HANDOFF.md,docs/ENTITIES.md,docs/DESIGN_PATTERNS.md, ordocs/FLOWS.mdwhen the area they cover changes. - Project docs, code identifiers, and translation keys stay in English; only
src/locales/<locale>/values are translated.
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.
- 6d ago First seen · 41 lines · 674 tokens per session scan A 6500a783d403
arthur-mcp CLAUDE.md is an instructions file published in the GitHub repository alexmmatos/arthur-mcp (2 stars, last pushed 1mo ago), licensed MIT. It adds 674 tokens to every session, about $0.0034 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 2026-09-03.
Other instructions, from other repositories
next.js AGENTS.md
AGENTS.md instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.
codex AGENTS.md
AGENTS.md instructions for openai/codex, covering rust/codex-rs, the codex-core crate, code review rules, crate api surface and model visible context.
vscode buildNext.instructions.md
Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).
vscode oss-third-party-notices.instructions.md
Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, applying the notice (cutover) and fallback chain (never fail the build).
langchain AGENTS.md
AGENTS.md instructions for langchain-ai/langchain, covering global development guidelines for the langchain monorepo, corridor security analysis, project architecture and context, monorepo structure and development tools & commands.
deepseek-harness AGENTS.md
AGENTS.md instructions for deepseek-ai/deepseek-harness, covering agents.md, pre-stable apis and released session data, repository layout, commands and host sandbox failures.