mcp-base CLAUDE.md

mcp-base CLAUDE.md is an instructions file for coding agents from yone-k/mcp-base. It costs 1,737 tokens per session, scanned A, original, MIT.

A TypeScript starter project for building an MCP server, a service that lets compatible AI clients use defined tools.

In plain words
What is it for?
Use it to create MCP tools with a registry, shared validation and error handling, TypeScript types, Vitest tests, and a Node.js entry point.
Why use it?
It gives developers an organised starting structure instead of creating the server architecture from scratch.

Instructions file

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add instructions/yone-k/mcp-base/claude-md
Clone the repo
git clone --depth 1 https://github.com/yone-k/mcp-base

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.

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README.md
[![agentmods](https://agentmods.dev/badge/instructions/yone-k/mcp-base/claude-md.svg)](https://agentmods.dev/instructions/yone-k/mcp-base/claude-md)
Your own site
<a href="https://agentmods.dev/instructions/yone-k/mcp-base/claude-md"><img src="https://agentmods.dev/badge/instructions/yone-k/mcp-base/claude-md.svg" alt="Measured on agentmods" height="20"></a>
Per session 1,737 This file is loaded in full into every session.
When invoked 1,737 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
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 $0.01737 $0.01737
Opus 5 $0.00869 $0.00869
Sonnet 5 $0.00347 $0.00347
Haiku 4.5 $0.00174 $0.00174

Measured 5d ago against content hash b2694397419f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

mcp-base 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 5d 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 · 215 lines

How it starts

The opening of the file, as written. The whole thing — 215 lines — stays where its author put it; the contents beside it link to each section on GitHub.

MCP Base Server

プロジェクト概要

汎用的なMCP (Model Context Protocol) サーバーのベーステンプレートです。新しいMCPサーバーを簡単に作成できるように設計されています。

技術スタック

  • 言語: TypeScript
  • フレームワーク: MCP SDK (@modelcontextprotocol/sdk)
  • バリデーション: Zod
  • 実行環境: Node.js 22+
  • テストフレームワーク: Vitest

アーキテクチャ

設計方針

MCPプロトコル準拠: Model Context Protocolの仕様に完全準拠し、標準的なMCPクライアントとの互換性を保つ モジュラー設計: ツール実装を独立したモジュールとして管理し、拡張性を重視 型安全性: TypeScriptとZodを活用した厳密な型チェック テンプレート性: 新しいMCPサーバー開発の出発点として使用可能

ディレクトリ構造

mcp-base/
├── src/
│   ├── core/              # MCPサーバーのコア機能
│   │   └── tool-handler.ts    # 共通ツールハンドラー
│   ├── tools/             # MCPツール実装(カテゴリ別整理)
│   │   ├── registry.ts         # ツールレジストリ
│   │   └── example/            # サンプルツール実装
│   ├── types/             # 型定義
│   └── index.ts           # エントリーポイント
├── package.json           # 依存関係とスクリプト
├── tsconfig.json          # TypeScript設定
├── vitest.config.ts       # テスト設定
├── README.md              # 使用方法
└── CLAUDE.md              # このファイル

ツール管理アーキテクチャ

ツールレジストリパターン: 各ツールファイルにMCP定義を含め、registry.tsで一元管理 動的ツール登録: index.tsはレジストリから動的にツール一覧を取得 共通ハンドラー: ToolHandlerクラスがバリデーションとエラーハンドリングを統一

開発ガイドライン

コーディング規約

  • ファイル命名: kebab-case (例: example-tool.ts)
  • クラス命名: PascalCase (例: BaseMCPServer)
  • 関数・変数命名: camelCase (例: setupHandlers)
  • 定数命名: UPPER_SNAKE_CASE (例: DEFAULT_TIMEOUT)
  • 型命名: PascalCase with suffix (例: ExampleToolInput)

新規ツール追加フロー

  1. カテゴリの決定: 追加するツールが属するカテゴリを決定
  2. ツールファイルの作成: src/tools/{category}/{tool-name}.ts
  3. ツール定義の実装: 以下の要素を含める
    • 入力スキーマ(Zod)
    • 出力スキーマ(Zod)
    • ツール定義(MCP形式)
    • 実装関数
  4. レジストリへの登録: src/tools/registry.tsに追加
  5. ハンドラーの更新: src/core/tool-handler.tsのswitchケースに追加
  6. テストの作成: src/tools/{category}/{tool-name}.test.ts

開発コマンド

# Docker環境での開発
npm run docker:build    # Dockerイメージをビルド
npm run docker:run      # Dockerコンテナを実行
npm run docker:dev      # Docker Composeで開発環境を起動

# ローカル開発
npm run dev

# テスト実行
npm test
npm run test:watch      # 監視モード
npm run test:coverage   # カバレッジ付き

# ビルド
npm run build

# lint/typecheck
npm run lint
npm run typecheck

Read the full file on GitHub · 215 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. 5d ago First seen · 215 lines · 1,737 tokens per session scan A b2694397419f

Subscribe to this mod's changes

mcp-base CLAUDE.md is an instructions file published in the GitHub repository yone-k/mcp-base (0 stars, last pushed 1y ago), licensed MIT. It adds 1,737 tokens to every session, about $0.0087 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.

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