houjin-bangou-api-mcp: Instructions file for Codex

AGENTS.md

houjin-bangou-api-mcp AGENTS.md is an instructions file for Codex, OpenCode from yamayued/houjin-bangou-api-mcp. It costs 645 tokens per session, scanned A, original, MIT.

A set of contributor instructions for an MCP server that exposes Japan’s National Tax Agency corporate-number publication API. It explains public-repository safety rules, configuration, and expectations for implementing the API connection.

In plain words
What is it for?
Use it when building, configuring, documenting, or reviewing this MCP server and its connection to the Japanese corporate-number API.
Why use it?
It helps prevent secrets such as API keys, tokens, and cookies from being committed to a public code repository. It also keeps configuration and implementation practices consistent.

Instructions file for CodexOpenCode

Written for Codex and OpenCode: the file is AGENTS.md. Also seen: mentions AGENTS.md.

This is yamayued/houjin-bangou-api-mcp's own configuration. It tells Codex and OpenCode how to work on houjin-bangou-api-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 houjin-bangou-api-mcp configures →

Reuse

Borrowing it

Nothing to install: this file belongs to yamayued/houjin-bangou-api-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/yamayued/houjin-bangou-api-mcp/main/AGENTS.md
Clone the repo
git clone --depth 1 https://github.com/yamayued/houjin-bangou-api-mcp

Made for: Codex, OpenCode.

Wrote this? Show the measurements

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README.md
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<a href="https://agentmods.dev/instructions/yamayued/houjin-bangou-api-mcp/agents-md"><img src="https://agentmods.dev/badge/instructions/yamayued/houjin-bangou-api-mcp/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 645 This file is loaded in full into every session.
When invoked 645 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 $0.00645 $0.00645
Opus 5 $0.00322 $0.00322
Sonnet 5 $0.00129 $0.00129
Haiku 4.5 $0.00064 $0.00064

Measured 8d ago against content hash e7d7a1605f49, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

houjin-bangou-api-mcp AGENTS.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.

AGENTS.md · 78 lines

How it starts

The opening of the file, as written. The whole thing — 78 lines — stays where its author put it; the contents beside it link to each section on GitHub.

AGENTS.md

This repository is public. Treat every file, commit, issue, pull request, log snippet, and example value as if it may be read by anyone.

Purpose

This project provides a Model Context Protocol (MCP) server for the Japan National Tax Agency Corporate Number Publication Site Web-API.

Primary goals:

  • expose the official API through clear MCP tools
  • keep the server small, auditable, and easy to self-host
  • avoid bundling any private or organization-specific configuration

Public Repository Rules

  • Never commit API keys, application IDs, tokens, cookies, .env files, or captured responses that contain sensitive data.
  • Do not include real credentials in examples, tests, screenshots, logs, or documentation.
  • Use placeholders such as YOUR_APPLICATION_ID in docs and sample configs.
  • Keep all defaults safe for public open source use.
  • Do not assume access to private infrastructure, internal URLs, or paid services.

Configuration

  • Read secrets from environment variables only.
  • Document every required environment variable in README.md.
  • Provide a checked-in example file such as .env.example when configuration is added.
  • Fail with a clear error message when required configuration is missing.

API Implementation Expectations

  • Follow the official National Tax Agency Web-API documentation and prefer the latest supported version.
  • Keep request/response handling close to the official field names unless there is a strong MCP usability reason to normalize them.
  • Preserve important source metadata so users can trace MCP output back to the official API.
  • Be explicit about rate limits, pagination, and error handling in code and docs.
  • If the official API behavior is unclear, add a note to the docs instead of guessing silently.

Coding Standards

  • Prefer TypeScript for the MCP server unless the repository already adopts another stack.
  • Keep dependencies minimal and choose well-maintained packages.
  • Favor simple modules over framework-heavy abstractions.
  • Add comments only when they help explain non-obvious behavior.
  • Avoid hard-coding Japanese text directly in shell inline commands. If shell execution needs Japanese text, read it from a UTF-8 .txt or .json file.

Read the full file on GitHub · 78 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 · 78 lines · 645 tokens per session scan A e7d7a1605f49

Subscribe to this mod's changes

houjin-bangou-api-mcp AGENTS.md is an instructions file published in the GitHub repository yamayued/houjin-bangou-api-mcp (1 stars, last pushed 6mo ago), licensed MIT. It adds 645 tokens to every session, about $0.0032 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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