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@0.14.1        # 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) and PRIORS_RPC (another Robinhood Chain node). Any other setting stays at @priors/mcp's default.

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

1. credit_status reads the agent's own line, the amount available and its open loans.
2. agent_record(agent_id) on the read-only server reads another agent's record: its line, repaid and late loans, defaults and score.
3. 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.
4. 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. 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

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