Priors for Hermes Agent

A Portable Agent Plugins v1 package for Hermes Agent. It lets a Hermes agent pay HTTP 402 (x402) APIs on credit: when its wallet is short, it borrows the gap in USDG from its Priors credit line on Robinhood Chain, pays, and repays. Before paying another ERC-8004 agent it can read that agent's repayment record.

It bundles two MCP servers and one skill:

Server	What it is	Moves money
`priors`	the hosted, read-only Priors MCP server, `https://mcp.priors.trade/mcp` (no key, no sign-in)	no
`priors-wallet`	the local `priors-mcp` command from npm `@priors/mcp`, signing with the agent's own wallet	yes
`skills/priors`	when to use the tools, in what order, and what to confirm with the user first	no

Install

npm install -g @priors/mcp@0.15.0        # the priors-mcp command
hermes plugins install priors            # once listed in Hermes's plugin catalog
hermes plugins enable priors             # portable packages install disabled

Then, in the Hermes profile's .env:

PRIORS_KEY_FILE=/path/to/agent-wallet.key   # chmod 600; a dedicated wallet, never a main one
PRIORS_AGENT_ID=1234                        # the agent's ERC-8004 id
PRIORS_PAY_HOSTS=check.blockpin.dev         # the only hosts pay_url may pay
PRIORS_STATE_DIR=~/.priors/state           # where the daily caps and sent payments are kept
PRIORS_MAX_SPEND_DAY_USD=5                  # optional daily caps
PRIORS_MAX_BORROW_DAY_USD=5

Hermes hands the server only the variables mcp.json names, so these are the ones that reach it: the five above, PRIORS_KEY (instead of PRIORS_KEY_FILE), PRIORS_MAX_PRICE_USD (most a call, default 1.00), PRIORS_MAX_BORROW_USD (most a borrow, default 25), PRIORS_MAX_SPEND_USD and PRIORS_MAX_BORROW_TOTAL_USD (totals while the server runs, defaults 5 and 25), PRIORS_AUTO_BORROW_USD (auto-borrow, off by default, below) and PRIORS_RPC (another Robinhood Chain node). Any other setting stays at @priors/mcp's default.

Inference on credit (@priors/mcp 0.15.0 or later): pay_url can buy one OpenAI-style chat completion from agent402.tools (url https://agent402.tools/v1/chat/completions, method POST, the request as body, paid in USDG on Robinhood Chain). With PRIORS_AUTO_BORROW_USD set (for example 5, with PRIORS_MAX_BORROW_DAY_USD=10 and agent402.tools in PRIORS_PAY_HOSTS), a call that names no max_borrow_usd borrows the gap on its own, for 14 days, only while the agent wallet's Autopay covers the loan, which then repays it in its window. Unset, borrowing stays the max_borrow_usd the user approves in each call.

priors-mcp is a Node.js command, so node must be on the PATH Hermes runs with. It signs nothing when PRIORS_STATE_DIR sits under a directory other users can write to (its record of sent payments and daily totals could be tampered with): use a directory only you can write to (chmod 700), with no group- or world-writable parent.

Without a key only the read-only priors server is useful: records, sellers, pool data.

What it does

credit_status reads the agent's own line, the amount available and its open loans.
agent_record(agent_id) on the read-only server reads another agent's record: its line, repaid and late loans, defaults and score.
pay_url(url, max_price_usd, max_borrow_usd) fetches the URL; on HTTP 402 it pays in USDG at or below max_price_usd, and if the wallet is short it borrows the gap from the line when max_borrow_usd covers it. A loan is at least the pool's minimum (5 USDG today), so a 0.10 payment from an empty wallet borrows 5.
repay(loan_id) repays the loan, principal and fee.

Disclosure

Payments and loans are real money: USDG on Robinhood Chain mainnet, signed by the key in PRIORS_KEY_FILE (or PRIORS_KEY) in the Hermes profile's .env.
Both servers are marked untrusted, so Hermes asks the user before every tool call that is not read-only, including every payment, borrow and repayment. The plugin never auto-approves one. Where nobody can answer (hermes chat -q, cron, the messaging gateway without a prompt), Hermes declines the call and nothing is paid.
pay_url pays only the hosts in PRIORS_PAY_HOSTS, never more than max_price_usd a call (and the server's PRIORS_MAX_PRICE_USD, 1.00 by default), and borrows only when max_borrow_usd is given, or, with PRIORS_AUTO_BORROW_USD set by the user, on its own within that setting while Autopay covers the loan (the approval prompt shows the call's arguments, not that setting). The server's own totals (PRIORS_MAX_SPEND_USD 5 and PRIORS_MAX_BORROW_TOTAL_USD 25 by default while it runs, and the daily caps above) bound what one session can spend or borrow.
A loan more than three days late can be marked defaulted, which ends the agent's record on Priors.
The hosted server receives the tool calls' public arguments (agent ids, addresses) and counts each connection by the client's runtime name only: https://mcp.priors.trade/privacy.
The tools are served by @priors/mcp and by the hosted server; their code is open in https://github.com/priors-agents/priors.

Demo

Hermes Agent paying an x402 API on credit with this plugin

A production run in Hermes Agent 0.22.5 on 2026-10-30 (agent #437, Robinhood Chain mainnet), cut to 58 seconds at 1.6x speed. The agent reads the seller's record (Blockpin, agent #9233), then pays its x402 check (0.10 USDG) from an empty wallet: pay_url borrows 5 USDG, the pool's minimum loan (loan #50891), after Hermes asks and the user allows it once. The agent's income then arrives from another wallet, and repay closes the loan for 5.011666 USDG. Transactions: borrow, payment, repayment.

License

MIT