MCP server

Connect

The bearer token is an ordinary zScreen API key, the same one the HTTP API takes. Sign in at /signin with Google or a wallet, then create a key from /dashboard. It is shown once, on that screen, so copy it before navigating away. Paste it in place of zsk_... below.

In Claude Code:

claude mcp add --transport http zscreen \
  https://zscreenapi.zeruai.org/mcp \
  --header "Authorization: Bearer zsk_..."

Clients that take a configuration file, such as Cursor and VS Code, want the same three things: the transport, the URL, and the header.

{
  "mcpServers": {
    "zscreen": {
      "type": "http",
      "url": "https://zscreenapi.zeruai.org/mcp",
      "headers": { "Authorization": "Bearer zsk_..." }
    }
  }
}

Clients that only offer OAuth fields, which includes the Claude web connector, cannot use a key header yet. Use Claude Code, Cursor or VS Code until that lands.

Tools

• screen_wallet(address) screens one address and returns the verdict.
• get_job(job_id) polls a wallet that had to be fetched.
• get_screening(screening_id) returns one record from your account.
• list_wallet_screenings(address) lists your screenings for an address.

Read assessed first

Every result carries an assessed field, and it is the one to branch on. Only a result with assessed: true carries a verdict.

{
  "ok": true,
  "assessed": true,
  "verdict": "FLAGGED",
  "risk_score": 100,
  "decided_by": {
    "rule": "ofac_contact",
    "source": "rule",
    "reason": "This wallet dealt directly with an address on the OFAC sanctions list."
  }
}

A wallet nobody has looked at yet comes back with assessed: false and a null verdict. It is not a clean wallet. The same is true when the free tier is spent and when the chain has nothing to score.

{
  "ok": true,
  "assessed": false,
  "status": "queued",
  "job_id": 41,
  "verdict": null,
  "note": "This wallet has no history on file and is being fetched. Poll get_job with job_id. A wallet is NOT low risk because it has not been assessed yet."
}

Rate limits and brief outages also return assessed: false, with a retry_after, so a failure to answer is never mistaken for an answer.

Limits

Tool calls are screens. They count against the same free tier and the same requests-per-second limit as the API, on the key you configured, so Rate limits and the free tier applies unchanged.

When the key's free tier is spent, screen_wallet returns assessed: false with status: "payment_required" and a payment object. The agent cannot pay from inside MCP: a person, or an x402 client, pays $0.50 per screen over the HTTP API.

No MCP in your client?

An agent can call the HTTP API directly instead. skill.md is a single file that tells it how, and For agents covers the rest of what this site offers machines.