FractalAI MCP Server

A Model Context Protocol (MCP) server that exposes FractalAI's live post-quantum cryptography and x402 micropayment capabilities as tools any MCP client (Claude Desktop, IDEs, agent frameworks) can call over stdio.

It talks to the real, public FractalAI deployment at https://fractalai.net.co — nothing here is mocked.

What it does

| Tool | Cost | What it does | |------|------|--------------| | verify_proof | free | Verify a post-quantum Dilithium-2 / NIST FIPS 204 signature against its public key. Returns { valid, verdict }. | | x402_checkout | free | Return live x402 (HTTP 402) payment requirements for a paid resource — price, network, USDC asset, payTo, and the accepts[] entries. Also fetches the full .well-known/x402.json manifest. | | pqc_sign | $0.02 USDC | Buy one Dilithium-2 signature over a message (its sha256 is signed) or a hex hash (signed directly). | | seal_provenance | $0.05 USDC | Buy a PQC + drand provenance seal over content: a drand round + a Dilithium-2 signature + an on-chain anchor attempt over the content hash. | | attest_decision | $0.05 USDC | Seal an AI agent's declared decision (input hash, output, model, timestamp) — Dilithium-2 signed, Black-Box chained, on-chain anchored (VAID-1). Returns a re-verifiable receipt. |

Honest scope (read this)

• Dilithium-2 is resistant to known classical and quantum attacks per NIST FIPS 204 — it is NOT "unbreakable". A signature proves the exact bytes you submitted were signed by this server's post-quantum key. It says nothing about the truthfulness of the signed content.
• seal_provenance produces a provenance record, not a content audit.
• attest_decision notarizes a decision as declared; it does not judge whether the decision was correct.
• The paid tools run a real HTTP 402 flow. Without a payment_tx_hash they return the payment challenge (accepts[]) — they never fabricate a result.

Payment model (x402)

Paid tools are gated by x402: pay in USDC on Base to the service's treasury, then the tool returns the resource. This server uses the facilitator-less txHash settlement path, which needs no facilitator account:

1. Call the tool once with no payment_tx_hash. You get back the accepts[] block: the exact USDC amount, the asset (USDC on Base), and the payTo treasury address.
2. Send that USDC transfer on Base yourself.
3. Call the tool again with payment_tx_hash set to the confirmed transaction hash. One txHash buys exactly one call (anti-replay is enforced server-side).

verify_proof and x402_checkout are always free.

Install & build

cd integrations/mcp
npm install
npm run build

Configure in an MCP client

Claude Desktop (claude_desktop_config.json)

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

Any stdio MCP client

Run the built entrypoint: node dist/index.js. It speaks MCP over stdio; all logging goes to stderr so stdout stays a clean JSON-RPC channel.

Environment

• FRACTALAI_BASE_URL — override the endpoint base (defaults to https://fractalai.net.co).

Example flows

Verify a signature (free):

{
  "name": "verify_proof",
  "arguments": {
    "signed_message_b64": "<base64 of the exact bytes that were signed>",
    "signature": "<base64 Dilithium-2 signature>",
    "public_key": "<base64 Dilithium-2 public key>"
  }
}

Price a signature (free), then buy it (paid):

{ "name": "x402_checkout", "arguments": { "resource": "sign" } }

{ "name": "pqc_sign", "arguments": { "message": "hello world" } }

The first pqc_sign call (no payment_tx_hash) returns the payment challenge. Pay the USDC, then call again:

{
  "name": "pqc_sign",
  "arguments": { "message": "hello world", "payment_tx_hash": "0x…" }
}

About FractalAI

FractalAI is an AI-native Layer 1 blockchain (chain id 62124) written in Rust with post-quantum cryptography (CRYSTALS-Dilithium signatures, Kyber encryption). These x402 endpoints sell post-quantum proof, provenance and decision-attestation services to autonomous agents. See https://fractalai.net.co and the discovery manifest at https://fractalai.net.co/.well-known/x402.json.

License

MIT