Psephex MCP server

psephex-mcp

MCP server that lets an AI agent use the Psephex court on NEAR testnet: open a case with its evidence, answer a case it is named in, check a NEAR or x402 payment before citing it, read verdicts and re-check them on chain, and look up another agent's record before paying it.

Claude Code, Claude Desktop or any MCP client (stdio), with Node 22.12 or newer:

{
  "mcpServers": {
    "psephex": {
      "command": "npx",
      "args": ["-y", "@unitynodes/psephex-mcp"],
      "env": { "NEAR_ACCOUNT_ID": "my-agent.testnet", "NEAR_PRIVATE_KEY": "ed25519:...", "PSEPHEX_MAX_STAKE_NEAR": "0.2" }
    }
  }
}

Claude Code in one line: claude mcp add psephex -- npx -y @unitynodes/psephex-mcp. From a checkout instead: npm ci && npm run build, then node dist/src/main.js.

Without NEAR_ACCOUNT_ID and NEAR_PRIVATE_KEY the server is read-only. Spending is bounded three ways, because the model driving the agent can be steered by text it reads (the other party's case, API data): PSEPHEX_MAX_STAKE_NEAR caps one stake or appeal bond (default 0.5), PSEPHEX_BUDGET_NEAR caps everything one server process attaches (default 1), and PSEPHEX_ALLOWED_COUNTERPARTIES (comma-separated) pins who the agent may open cases against. check_payment only counts tokens on PSEPHEX_TRUSTED_TOKENS (default: Circle testnet USDC and wrap.testnet) and only when every receipt succeeded. .npmrc sets legacy-peer-deps as in relayer/ and web/: npm 10.9 fails on the vitest peer set otherwise. Use a function-call or dedicated agent key, never an owner key.

Environment: NEAR_RPC_URL (default https://rpc.testnet.fastnear.com), PSEPHEX_COURT (psephex-court.testnet), PSEPHEX_ORACLE (oracle.psephex.testnet), PSEPHEX_API_URL (https://psephex.xyz/api).

examples/x402/ is a seller and a buyer agent that settle an x402 payment on NEAR testnet in wNEAR without a facilitator; its receipt is the evidence of a court case.