byte-mcp-server Server

Per-byte USDC data feeds + oracles for AI agents on Arbitrum. 14 tools, EIP-712 attested payloads, no API keys, no token. MCP server for the BYTE Library catalog (18+ first-party publishers).

GitHub

Documentation

BYTE Library MCP Server

A Model Context Protocol server that gives AI agents direct access to BYTE Library — per-byte USDC data feeds on Arbitrum. Agents discover feeds, subscribe to streams, or pay-per-call for one-off data via x402. Every settlement carries an EIP-712 PayloadAttestation receipt. No tokens, no API keys, no off-chain accounts: settle in USDC, route through MCP.

🧪 Testnet only. This release targets Arbitrum Sepolia (chain 421614). Use a testnet-only wallet — never configure PRIVATE_KEY to a key holding mainnet funds. Get free Sepolia ETH from any Arbitrum Sepolia faucet. Mainnet (Arbitrum One) is the next milestone, gated on the Pashov security audit.

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 BYTE Library catalog" / "Search publishers for weather"
Buy one packet (x402, no setup): "Buy the latest weather data" → ~$0.021 USDC, ~3 seconds, on-chain receipt
Subscribe to a stream: "Subscribe me to the earthquakes feed" → auto-approves USDC for ongoing settlement
Query a fact: "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 — 15 feeds across weather, markets, code, security, knowledge.

Two paradigms: subscribe vs. buy

Mode	Tool	Best for	Pricing
Subscribe	`byte_subscribe`	Continuous streams (every weather update, every new earthquake)	$0.003 USDC / KB per delivery
Buy (x402)	`byte_buy_data`	One-off needs (single snapshot for this user query)	$0.005 USDC / KB per call, $0.001 floor

Subscribe is cheaper per byte and gives the agent every broadcast; buy is zero-setup and pay-as-you-go. Pick by access pattern, not by price alone.

Tools (14 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

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. No subscription, no allowance. Signs EIP-3009 `transferWithAuthorization`; 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	—	Arbitrum Sepolia wallet key
`RPC_URL`	no	`https://sepolia-rollup.arbitrum.io/rpc`	Arbitrum Sepolia RPC
`INDEXER_URL`	no	`http://localhost:8080`	BYTE Library indexer API
`BYTE_GATEWAY_URL`	no	`https://x402.payperbyte.io`	x402 gateway base URL (used by `byte_buy_data`)

Network

Current release targets Arbitrum Sepolia (chain 421614) — BYTE Library's testnet. Mainnet (Arbitrum One) is the next milestone, gated on the external security audit. Contract addresses are pinned in the bundled config; the npm release ships ready-to-use defaults.

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.