PayPerByte MCP Server

A Model Context Protocol server that gives AI agents direct access to PayPerByte — verified, provenance-first data feeds for AI agents. Agents discover feeds, pay-per-call via x402 (settled in USDC on Base mainnet), or subscribe to on-chain streams (Arbitrum Sepolia testnet). Every paid x402 response carries an EIP-712 PayloadAttestation receipt (X-BYTE-Attestation header) the agent verifies before acting. No tokens, no API keys, no off-chain accounts.

Two rails — read this before setting PRIVATE_KEY.

• x402 pay-per-call (byte_buy_data): Base mainnet (eip155:8453), REAL USDC. Paid feeds settle real money — the flagship Address Reputation Oracle is $0.05 per verdict. Use a dedicated wallet holding only what you intend to spend.
• On-chain subscribe/publish/query layer (BYTE Library contracts + indexer): Arbitrum Sepolia testnet (chain 421614), MockUSDC. Mainnet for this layer is gated on an external security audit. The EIP-712 attestation signing domain stays anchored at 421614 regardless of which rail you paid on.

One PRIVATE_KEY serves both rails. Never reuse a key holding funds you can't afford to spend.

Verify before acting (ForeSeal)

See the whole verify-before-act loop in one command — no install, no signup, no wallet:

npx @foreseal/demo

It runs locally (no real USDC) and shows an agent ACT on genuine bytes and REFUSE four attacks — a tampered byte, a forged signature, a missing receipt, a forked signing domain — in about a second.

The same primitive ships as two packages you can drop into your own stack:

• Kit — @payperbyte/sdk: the buyer verifies a receipt before acting.
• Gate — @foreseal/gate: a seller stamps a verifiable receipt on any x402 endpoint.

Two paradigms: subscribe vs. buy

Buy is zero-setup, pay-as-you-go, and live with real settlement; subscribe delivers every broadcast on the audit-gated testnet layer. Pick by access pattern.

Tools (15 total)

Discovery (read-only, no wallet)

Subscribe to a stream (requires PRIVATE_KEY)

Buy on-demand (requires PRIVATE_KEY)

Network

Two rails, honestly stated:

• x402 payment rail (byte_buy_data): Base mainnet (eip155:8453). Paid feeds settle real USDC through the gateway at x402.payperbyte.io; each paid 200 returns an X-BYTE-Attestation EIP-712 receipt over the exact response bytes.
• On-chain layer (subscriptions, broadcasts, fact-oracle escrow, indexer): Arbitrum Sepolia (chain 421614). Mainnet for the BYTE Library contracts is gated on an external security audit. The EIP-712 PayloadAttestation signing domain is anchored on 421614 regardless of the payment rail.

Contract addresses are pinned in the bundled config; the npm release ships ready-to-use defaults. No token.

Development

git clone https://github.com/0rkz/byte-mcp-server.git
cd byte-mcp-server
npm install
npm run build && npm start

Links

• payperbyte.io — PayPerByte home
• x402.payperbyte.io/feeds — live feed catalog
• Model Context Protocol — MCP spec
• MCP TypeScript SDK

Quick start

npx -y byte-mcp-server

Wire it into your MCP client (Claude Desktop config below), then your agent can:

• Discover feeds: "List the PayPerByte catalog" / "Search publishers for weather"
• Buy one packet (x402, no setup): "Check this receiving address before I pay it" → $0.05 real USDC on Base mainnet, signed ALLOW/WARN/BLOCK verdict with an attestation receipt
• Subscribe to a stream (testnet): "Subscribe me to the earthquakes feed" → auto-approves MockUSDC for ongoing settlement on Arbitrum Sepolia
• Query a fact (testnet): "Ask the fact-oracle who won the last Lakers vs Warriors game" → on-chain signed answer with citations

The live catalog is at x402.payperbyte.io/feeds — verified, provenance-first feeds across weather, markets, code, security, and knowledge.

Configuration

Claude Desktop

Edit ~/.config/claude/claude_desktop_config.json (Linux) or ~/Library/Application Support/Claude/claude_desktop_config.json (macOS):

{
  "mcpServers": {
    "byte-library": {
      "command": "npx",
      "args": ["-y", "byte-mcp-server"],
      "env": {
        "PRIVATE_KEY": "0x...",
        "RPC_URL": "https://sepolia-rollup.arbitrum.io/rpc",
        "INDEXER_URL": "http://localhost:8080"
      }
    }
  }
}

PRIVATE_KEY is optional — read-only tools work without it. Add it to enable subscribe, publish, buy, and query.

Claude Code

claude mcp add byte-library -- npx -y byte-mcp-server

Environment variables

License

MIT — see LICENSE.