ARES (Czech business registry) MCP server

ares-mcp

MCP server for ARES — the Czech business registry. Validate IČO/DIČ, look up companies, statutory bodies, trade licenses and addresses directly from Claude Desktop, Claude Code, Cursor and any other MCP-compatible client.

Open-source (MIT), self-hosted. Runs against the public ARES API — your queries never leave your machine. Optionally emits Ed25519-signed, sourced answers so anyone can verify their integrity and origin offline.

Hosted version: icovazby.cz — full web company-checks across 10+ Czech registers (ARES, Public Register, trade licenses, insolvency, sanctions, …).

ARES (Administrativní registr ekonomických subjektů) is the official public registry of Czech businesses, operated by the Czech Ministry of Finance (MFČR). This project is an independent, community-built MCP server that calls the public ARES REST API.

Not affiliated with the Czech Ministry of Finance. This project is not affiliated with, endorsed by, or sponsored by MFČR or the ARES operator. "ARES" refers to the public information system; this MCP server is third-party software.

• Free, MIT-licensed code. No API key required (ARES is a public API).
• 14 stable tools covering the full due-diligence + invoicing workflow: validation, lookup, structured search, search-by-address (virtual-office detection), statutory bodies, trade licenses, VAT check, address standardization, NACE lookup, RES statistical classification (size bracket, ESA 2010 sector), insolvency check, cross-company person graph with Mermaid + optional historical mode for nominee detection, a one-shot aresfullduediligence macro with 🟢🟡🔴 risk flag, and an export adapter** that emits Fakturoid / iDoklad / Pohoda payloads ready to POST.
• Two transports. Stdio (default) for local AI clients, Streamable HTTP (/mcp) for remote / web deployment.
• Verifiable provenance (optional). With a signing key set, the due-diligence, statutory-bodies and insolvency tools return a signed envelope where every fact carries its registry source + date; verify it offline against the published JWKS. A technical integrity & origin proof — not a qualified e-signature or an official extract.
• Defensive by design. Rate-limit aware (token bucket + exponential backoff with Retry-After), per-IP request throttling on the HTTP variant, structured errors, no PII stored or logged by default.

Setup

Two ways to run ares-mcp — pick one:

Option A — npx (no install, recommended)

{
  "mcpServers": {
    "ares": { "command": "npx", "args": ["-y", "@milos106/ares-mcp"] }
  }
}

Option B — from source

git clone git@github.com:milos106/ares-mcp.git
cd ares-mcp
npm install
npm run build
npm test

Then point your MCP client at the absolute path of dist/index.js. The per-client examples below use this from-source form — swap "command": "node", "args": ["…/dist/index.js"] for the npx form above if you prefer a zero-install setup.

Claude Desktop

Edit your claudedesktopconfig.json:

• macOS: ~/Library/Application Support/Claude/claudedesktopconfig.json
• Windows: %APPDATA%\Claude\claudedesktopconfig.json
• Linux: ~/.config/Claude/claudedesktopconfig.json

{
  "mcpServers": {
    "ares": {
      "command": "node",
      "args": ["/absolute/path/to/ares-mcp/dist/index.js"]
    }
  }
}

Restart Claude Desktop.

Claude Code

claude mcp add ares -- node /absolute/path/to/ares-mcp/dist/index.js

Cursor

In Cursor settings → MCP servers:

{
  "ares": {
    "command": "node",
    "args": ["/absolute/path/to/ares-mcp/dist/index.js"]
  }
}

Get ready-to-paste client config

After npm run build, this prints absolute-path config blocks for Claude Desktop, Cursor, Claude Code, and the local HTTP transport:

npm run config

Shortened. The full README is on GitHub.