Borrowing it
Nothing to install: this file belongs to syumai/go-mcp-hands-on. 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/syumai/go-mcp-hands-on/main/CLAUDE.mdgit clone --depth 1 https://github.com/syumai/go-mcp-hands-onWrote 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/syumai/go-mcp-hands-on/claude-md)<a href="https://agentmods.dev/instructions/syumai/go-mcp-hands-on/claude-md"><img src="https://agentmods.dev/badge/instructions/syumai/go-mcp-hands-on/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/syumai/go-mcp-hands-on/claude-md"><img src="https://agentmods.dev/badge/instructions/syumai/go-mcp-hands-on/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 | $0.00506 | $0.00506 |
| Opus 5 | $0.00253 | $0.00253 |
| Sonnet 5 | $0.00101 | $0.00101 |
| Haiku 4.5 | $0.00051 | $0.00051 |
Grade A, and why
go-mcp-hands-on 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 12d 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.
What it actually says
CLAUDE.md
This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
プロジェクト概要
これはGo言語でMCP（Model Context Protocol）サーバーを実装するハンズオン資料のリポジトリです。caesar-mcpディレクトリに実装されたシーザー暗号のMCPサーバーが含まれています。
アーキテクチャ
- caesar-mcp/: メインのMCPサーバー実装
main.go: MCPサーバーのエントリーポイントserver/server.go: MCPサーバーの定義とツール登録caesar/caesar.go: シーザー暗号のコア実装（RotN関数）server/server_test.go: MCPサーバーのテスト
- docs/: ハンズオン資料（Markdown形式）
- examples/: サンプルコード
重要なコマンド
ビルドとテスト
# caesar-mcpディレクトリに移動
cd caesar-mcp
# プロジェクトをビルド
go build
# テスト実行
go test ./...
# MCPサーバーを実行（stdioモード）
go run main.go
MCP実装の構造
このプロジェクトでは github.com/mark3labs/mcp-go ライブラリを使用してMCPサーバーを実装しています：
server.NewMCPServer()でサーバーインスタンスを作成- サーバーにツール（caesar_rotate）を登録
server.ServeStdio()でstdio経由でMCPプロトコルを処理
現在の実装では、server.goのrotateHandlerが未実装の状態で、これがハンズオンの実装対象となっています。
テスト環境
- Caesar暗号の機能テスト:
caesar/caesar_test.go - MCPサーバーのツールテスト:
server/server_test.go
テストの一部が失敗する場合は、MCPツールの登録が未完了の可能性があります。
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.
- 12d ago First seen · 51 lines · 506 tokens per session scan A 1fed436de2bd
go-mcp-hands-on CLAUDE.md is an instructions file published in the GitHub repository syumai/go-mcp-hands-on (21 stars, last pushed 1y ago), licensed MIT. It adds 506 tokens to every session, about $0.0025 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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