Introduction

VulSight Guard sits between your agent and every payment. The agent proposes, the key's policy decides, and a person answers every review.

A new key's policy allows test USDC on Base Sepolia. Switch it to Base or Solana Mainnet for real USDC (supported payments). Start with the quickstart.

What it decides

allowedEvery rule passed. The payment goes ahead.

deniedA rule refused it. The SDK signs nothing, and the proxy never forwards the signed payment.

reviewHeld for a person on Review, two minutes by default.

What the agent sees while a payment is held

Lane	While held	When time runs out
Proxy URL	Holds an EVM payment up to 35 seconds. A Solana payment gets its answer at once.	Answers 402 `review_pending`. The review stays open on Review.
SDK	The hook waits for the answer, two minutes by default.	Throws, and nothing is signed.
MCP (advisory)	The tool call waits, two minutes by default.	The tool tells the agent not to pay.

Each answer lists the rules that ran, with a sentence for each rule that did not pass, apart from one note that repeats another (reason codes).

Lanes

A lane is how your agent reaches the guard. Pick the one that fits how it pays.

Lane	Badge	Works with
Proxy URL	Enforced	Any x402 client, in any language
SDK	Enforced on routed payments	A TypeScript agent on an x402 client
MCP	Advisory	Claude Code, Codex, or another MCP client
HTTP API	Advisory: your code acts	Your own code, in any language

advisory

The MCP tool is advisory. The agent chooses whether to ask. For a check it cannot skip, use the proxy URL or the SDK hook.

The proxy URL, the SDK, and the advisory MCP tool run the same checks. The HTTP API exposes them directly. Its status route needs no key.

Terminal

curl -s https://vulsight-guard.vercel.app/api/v1/status

Response

{
  "version": "dev",
  "database": "ok",
  "contentCheck": "ok",
  "contentCheckAt": "2026-09-03T21:08:36.718Z"
}

What it does not do

Holds no key of yours and never signs your payments, so it cannot move funds or reverse a settled payment.
Sees only what you route through it. An agent that skips it can still pay.
The content check can block or hold, never approve.

The security model covers the rest.

NextQuickstart