# postcode-japan.reference.prefectures

Get the complete list of all 47 Japanese prefectures with JIS codes, official names in kanji, hiragana, katakana, and English, plus geographic region. Use prefecture codes returned here as the "prefecture" filter in the postcode-japan.postal.search tool. Data source: postcode.teraren.com — MIT license, no auth required.

Agent View of the PolicyLayer registry record for `postcode-japan.reference.prefectures`. HTML page: https://policylayer.com/tools/io-github-whiteknightonhorse-apibase/postcode-japan.reference.prefectures

## Facts

- Tool: `postcode-japan.reference.prefectures`
- Server: Apibase (`apibase-mcp-client`) — https://policylayer.com/tools/io-github-whiteknightonhorse-apibase.md
- Install: `npx -y apibase-mcp-client`
- Homepage: https://github.com/whiteknightonhorse/APIbase
- Risk category: Read (Low risk)
- Registry record: grade F, identity unverified
- Server auth posture: open
- Server rate-limited: no
- Parameters: 1
- Recommended policy verdict: Allowed

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `_placeholder` | string | no | No parameters required. Returns all 47 Japanese prefectures with JIS code, names in kanji, hiragana, katakana, English, and region. |

Parameters from the server's own tool schema.

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "postcode-japan.reference.prefectures",
    "arguments": {}
  }
}
```

## Why postcode-japan.reference.prefectures is rated Low

Retrieves static reference data about Japanese prefectures with no side effects or mutations.

From the tool's own definition: "Get the complete list of all Japanese prefectures with codes and names."

## Use case

AI agents call postcode-japan.reference.prefectures to retrieve information from Apibase without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

## Recommended policy (PolicyLayer)

Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Apibase:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "postcode-japan.reference.prefectures": {}
  }
}
```

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## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=io-github-whiteknightonhorse-apibase · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/io-github-whiteknightonhorse-apibase