openrails-mcp

MCP server that lets an agent transact on the OpenRails USDC rail (Arc) over stdio. Opens and claims are gasless by default — routed through the keeper relay — and the server is non-custodial: it signs with its own configured account and never holds anyone else's keys.

Tools

| Tool | Purpose | |---|---| | openrails_config | Network config, the server signer address, and its USDC balance. Read-only. | | pay_link | Pay an OpenRails link — a RailsFlow request (the signer becomes the payer, gasless open) or a RailsCard (claimed to the signer). Returns the tx hash. | | create_request_link | Create a RailsFlow request link to receive payment. No signing/tx. | | issue_railscard | Issue a claimable RailsCard link (the server pre-signs as payer). Returns a claim link + paycardId. | | paycard_status | Read a paycard/stream state from chain by id. |

Configuration (env)

| Var | Default | Notes | |---|---|---| | OPENRAILS_MCP_SIGNER_KEY | — | Dev signer (raw key). Omit for read-only. For prod, wire a Turnkey/Privy account via openrails-sdk/adapters (see below). | | OPENRAILS_RPC_URL | https://rpc.testnet.arc.network | Public Arc RPC. | | OPENRAILS_CHAIN_ID | 5042002 | | | OPENRAILS_HUB_ADDRESS | 0x01EC…381d | ArcOpenRailsHubV1. | | OPENRAILS_USDC_ADDRESS | 0x3600…0000 | | | OPENRAILS_RELAY_URL | deployed keeper | Sponsors gas for opens/claims. | | OPENRAILS_APP_BASE_URL | https://openrails.pages.dev | Base for generated links. | | OPENRAILS_EXPLORER_BASE_URL | https://testnet.arcscan.app | |

Run

npm install && npm run build
OPENRAILS_MCP_SIGNER_KEY=0x... node dist/index.js   # stdio server

Register with an MCP client (e.g. Claude Desktop mcpServers):

{
  "openrails": {
    "command": "npx",
    "args": ["openrails-mcp"],
    "env": { "OPENRAILS_MCP_SIGNER_KEY": "0x..." }
  }
}

Smoke test: OPENRAILS_MCP_SIGNER_KEY=0x... node smoke.mjs [paycardId].

Signer is pluggable

The server builds its signer via the SDK account abstraction (openrails-sdk). Dev uses a raw key (ethersToSubmitter); for production swap in turnkeyToAccount (server wallets / agents) or privyToAccount (humans) from openrails-sdk/adapters/* in src/context.ts. Because the OpenRails Hub authenticates the signature (not msg.sender), any EOA-backed account works with no contract change.