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.

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.

Two paradigms: subscribe vs. buy

| Mode | Tool | Rail | Best for | Pricing | |---|---|---|---|---| | Buy (x402) | byte_buy_data | Base mainnet — real USDC | One-off needs (single snapshot or verdict for this user query) | Per-feed, quoted in the 402 challenge ($0.05 flagship; most feeds cents or less) | | Subscribe | byte_subscribe | Arbitrum Sepolia — testnet MockUSDC | Continuous streams (every weather update, every new earthquake) | $0.003 / KB per delivery |

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)

| Tool | Description | |---|---| | byte_search_publishers | Search publishers by topic and sort order | | byte_list_feeds | List the active feed catalog with prices and frequencies | | byte_get_publisher | On-chain info for one publisher (status, subscribers, messages, USDC revenue, schema) | | byte_get_network_stats | Network-wide stats: publishers, messages, total fees settled | | byte_check_subscription | Is subscriber subscribed to publisher? | | byte_list_my_subscriptions | All active subscriptions for a wallet — last 7d/30d messages + USDC spend | | byte_subscription_health | Content-drift signal for a publisher: stable / moderate / significant / unknown | | byte_get_token_balances | USDC + ETH balances on Arbitrum Sepolia | | byte_verify_payload | Verify-before-act. Recompute keccak256 of the bytes your agent received and check them against the publisher's on-chain EIP-712 PayloadAttestation — anchor with an expectedHash you hold or the settlement txHash (which also recovers the signer and confirms it's the named publisher). If verified: false, the data was tampered/corrupted in transit — don't act on it |

Subscribe to a stream (requires PRIVATE_KEY)

| Tool | Description | |---|---| | byte_subscribe | Subscribe to a publisher's stream. Auto-bundles USDC approve(max) unless skipAllowance: true (closes a silent-payment-failure footgun where the contract's allowance-skip path delivered data with amount=0) | | byte_unsubscribe | Unsubscribe — takes effect next block | | byte_register_publisher | Register as a data publisher (schema + on-chain registration). v1 is first-party only; stake = 0 | | byte_publish_data | Publish a payload to a subscriber via DataStream (settles fee in USDC). See migration notice above re: r2 |

Buy on-demand (requires PRIVATE_KEY)

| Tool | Description | |---|---| | byte_buy_data | Buy one packet from any feed via the x402 gateway — real USDC on Base mainnet. No subscription, no allowance. Signs EIP-3009 transferWithAuthorization against the 402 challenge; the facilitator settles on-chain. Returns the data + tx hash inline | | byte_query_fact | Ask a slashable fact-oracle publisher a question. Signed EIP-712 request (binds query to your wallet so leaked queries can't burn your escrow); the answer is broadcast on-chain to your address with citations |

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

| Variable | Required | Default | Description | |---|---|---|---| | PRIVATE_KEY | only for write/buy/query tools | — | EOA key. Signs real Base-mainnet USDC for byte_buy_data and testnet txs for subscribe/publish/query — use a dedicated wallet | | RPC_URL | no | https://sepolia-rollup.arbitrum.io/rpc | Arbitrum Sepolia RPC (the on-chain read/subscribe layer) | | INDEXER_URL | no | https://feeds.payperbyte.io | PayPerByte indexer API | | BYTE_GATEWAY_URL | no | https://x402.payperbyte.io | x402 gateway base URL (used by byte_buy_data) |

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

License

MIT — see LICENSE.

Links

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