# validate_dic

Validate a Czech DIČ (VAT ID). Format check: "CZ" + 8-10 digits. For 8-digit tail (legal entities) also runs MOD11 checksum against the embedded IČO.

Agent View of the PolicyLayer registry record for `validate_dic`. HTML page: https://policylayer.com/tools/dev-cz-agents-ares/validate-dic

## Facts

- Tool: `validate_dic`
- Server: Ares (`https://ares.cz-agents.dev/mcp`) — https://policylayer.com/tools/dev-cz-agents-ares.md
- Homepage: https://github.com/martinhavel/cz-agents-mcp
- Risk category: Read (Low risk)
- Registry record: grade C, identity unverified
- Server auth posture: open
- Server rate-limited: yes
- Parameters: 1 (1 required)
- Recommended policy verdict: Allowed

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `dic` | string | yes | Czech DIČ — e.g., "CZ26168685". Whitespace and case tolerated. |

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": "validate_dic",
    "arguments": {
      "dic": "<dic>"
    }
  }
}
```

## Why validate_dic is rated Low

The validate_dic tool performs input validation only (format checking and checksum verification). It does not retrieve, create, modify, or delete data; it does not execute code or trigger external operations; and it does not involve financial transactions. This is a deterministic validation function that returns pass/fail results, making it a Read operation with minimal security risk.

From the tool's own definition: "Tool description states it 'Validate a Czech DIČ (VAT ID)' with 'Format check' and 'MOD11 checksum' validation—purely a data validation/verification operation with no side effects, data retrieval, or modifications."

## Use case

AI agents call validate_dic to retrieve information from Ares 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 Ares:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "validate_dic": {}
  }
}
```

## Other tools on Ares (9)

- `check_vat_payer` — Read — https://policylayer.com/tools/dev-cz-agents-ares/check-vat-payer.md
- `get_bank_accounts` — Read — https://policylayer.com/tools/dev-cz-agents-ares/get-bank-accounts.md
- `get_history` — Read — https://policylayer.com/tools/dev-cz-agents-ares/get-history.md
- `get_statutaries` — Read — https://policylayer.com/tools/dev-cz-agents-ares/get-statutaries.md
- `lookup_by_ico` — Read — https://policylayer.com/tools/dev-cz-agents-ares/lookup-by-ico.md
- `search_by_address` — Read — https://policylayer.com/tools/dev-cz-agents-ares/search-by-address.md
- `search_by_nace` — Read — https://policylayer.com/tools/dev-cz-agents-ares/search-by-nace.md
- `search_companies` — Read — https://policylayer.com/tools/dev-cz-agents-ares/search-companies.md
- `watch_entity` — Write — https://policylayer.com/tools/dev-cz-agents-ares/watch-entity.md

## 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=dev-cz-agents-ares · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/dev-cz-agents-ares