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Sentinel402 Prompt Scanner
x402
Sentinel402 Prompt Scanner is a paid API for AI agents from pii-guardrail.chronokey.workers.dev, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-12).
Scans untrusted text or JSON payloads for prompt injection attacks, PII, and secret leakage, returning a risk score and block/allow decision
Price / call$0.01
Success—
StatusUnknown
How this service works
Paid tools for AI agents over x402: a PII and secret guardrail that scans outbound payloads, live citable data (crypto, weather, GitHub, sports, FX), and an RCP/1 retrieval server backed by that live data.
Output
Returns a JSON object with: a boolean ok field, an integer risk score (0–100), a decision string ('block' or 'allow'), per-severity counts of findings, an array of finding objects (each with rule ID, label, severity, confidence, and text excerpts with character offsets), total scanned characters, engine version, and x402 payment settlement details.
Example use cases
Guard agent against prompt injection
“I just scraped this webpage to feed into my agent's context — can you run it through Sentinel402 first to check for any prompt injection or instruction-override attempts and block it if the risk score is above 60?”
Screen outbound payload for PII
“Before my agent sends this JSON response to the user, scan it for any PII or secret leakage — only flag medium severity or higher and block it if anything critical shows up.”
Validate user message before LLM call
“This is a raw message from an untrusted user that I'm about to send to my LLM — can you check it for system-prompt exfiltration attempts or instruction overrides and tell me whether to block or allow it?”
Technical details
Endpoint
POSThttps://pii-guardrail.chronokey.workers.dev/v1/scan/prompt?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need a real-time, per-call prompt injection and PII guardrail for untrusted text entering or leaving an AI agent pipeline. It is purpose-built for LLM security use cases (instruction overrides, system prompt leaks, secret exfiltration) with confidence-scored findings and configurable block thresholds — making it preferable to generic content moderation APIs that lack prompt-injection–specific rules.
Side effects
- Payment not settled via x402 — returns 402 Payment Required
- Text exceeds 32,000 character limit — request rejected
- Both text and payload provided simultaneously — mutually exclusive fields
- Invalid rule ID in rules array — unknown rule error
- Invalid minSeverity enum value — validation error
- Network timeout on Cloudflare Worker — transient 5xx error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| text | string | Untrusted text to inspect (web page, tool output, email, user message). Mutually exclusive with payload. Max 32000 chars. |
| rules | array | Explicit rule ids (see GET /prompt-rules). |
| enable | array | |
| disable | array | |
| payload | — | Any JSON to inspect instead of raw text (stringified, then scanned). |
| minSeverity | string | Only report findings at or above this severity. |
| blockThreshold | number | Risk score (0-100) at which the verdict becomes block. Default 60. |
Output
Schema · Response
{
"type": "json",
"example": {
"ok": true,
"risk": 88,
"x402": {
"network": "eip155:8453",
"settled": true,
"facilitator": "https://api.cdp.coinbase.com/platform/v2/x402",
"transaction": "0xabc123"
},
"cpuMs": 0.4,
"counts": {
"low": 0,
"high": 0,
"medium": 0,
"critical": 2
},
"engine": "sentinel402-prompt/1",
"decision": "block",
"findings": [
{
"rule": "PI_INSTRUCTION_OVERRIDE",
"count": 1,
"label": "Instruction-override attempt",
"samples": [
{
"end": 56,
"start": 24,
"excerpt": "ignore all previous instructions",
"confidence": 0.95
}
],
"severity": "critical",
"confidence": 0.95
},
{
"rule": "PI_SYSTEM_PROMPT_LEAK",
"count": 1,
"label": "System-prompt exfiltration attempt",
"samples": [
{
"end": 84,
"start": 61,
"excerpt": "reveal your system prompt",
"confidence": 0.93
}
],
"severity": "critical",
"confidence": 0.93
}
],
"truncated": false,
"scannedChars": 84,
"engineVersion": "1.0.0"
}
}Tags
x402
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