verglas-pay — MCP server

Give any LLM agent a spending envelope it cannot exceed. The agent asks; the vault contract answers. Keys stay on your machine, rules live on-chain, refusals come back by name.

Tools

| tool | what it does | | --- | --- | | verglas_status | the vault's rules, budget spent/left, frozen state, whitelist | | verglas_pay | pay USDC from the vault — the contract enforces whitelist, per-payment limit, daily limit, budget, freeze | | verglas_pay_x402 | buy from any x402-gated API — the payment float refills only through the vault, so the same rules govern x402 buying | | verglas_check | any agent's public record: cleared at the gate, seal score/age, stamp history |

Install

From npm (once published):

claude mcp add verglas --env PRIVATE_KEY=0x… -- npx verglas-mcp

From the repo:

npm install            # in mcp/
claude mcp add verglas -- npx tsx <repo>/mcp/index.ts

Environment (process env; inside the repo, the root .env also works):

• PRIVATE_KEY — the agent key (see below). Must be the agent of the vault to pay; any key can read.
• VERGLAS_NETWORK — fuji (default) or avalanche.
• VERGLAS_AGENT_ID — default agent id for status/pay/check (default 219).
• VERGLAS_X402_AGENT_ID — the x402 float vault's agent id (default 223).

The key story — never give this server your owner key

The vault knows two roles and they should be two different keys:

• Owner — creates the vault, sets the rules, freezes, withdraws. This key lives in your wallet and never touches this server.
• Agent — the only address allowed to call spend(), and only inside the rules. This is the key you hand to the MCP server.

Setup: generate a fresh key (cast wallet new), fund it with a little gas, and pass its address as agent when you create the vault in the console. Give the private key to this server via PRIVATE_KEY. If the agent key ever leaks, the damage is capped by the vault's rules — per-payment limit, daily limit, budget, whitelist — and one freeze() from the owner ends it entirely. For x402 buying the same logic stacks once more: the agent wallet holds only a tiny float, refilled through the vault on demand.

What it looks like

> pay 0.25 USDC to 0x…A1
PAID 0.25 USDC to 0x…A1
  tx: https://testnet.snowtrace.io/tx/0xfe59…
  budget after: 6.8 USDC of 10 USDC

> pay 6 USDC to 0x…A1
REFUSED by the vault: PerTxLimitExceeded(6000000, 5000000) — the payment
never left. Rules live in the contract, not in this tool.

> fetch https://verglas-x402-demo.l3ekirerdem.workers.dev/frost-report
float refill through vault (agent #223):
  PAID 0.01 USDC to 0xc092…2Ad6
PAID 0.01 USDC over x402 to 0x26e5…709B
  settlement tx: https://testnet.snowtrace.io/tx/0xb5f2…

The refusal is not this server being careful — verglas_pay simulates and submits; the contract refuses. Delete this server, write your own, the rules hold.

Smoke run

npx tsx smoke.ts            # reads + two named refusals, nothing spent
npx tsx smoke.ts --pay 0.25 # …plus one real in-rule payment
npx tsx smoke.ts --x402 <url> # …plus a real paid fetch through the float vault

Publishing

npm run build bundles the server (SDK inlined) into dist/index.js; npm publish runs it automatically. The package ships as verglas-mcp with a matching npx bin.