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Verdict L402 – Agent Prompt Injection & Action Firewall
x402
Verdict L402 – Agent Prompt Injection & Action Firewall is a paid API for AI agents from verdict.kechlab.com, paid per call via x402, $0.0255/call, status unknown (last checked 2026-10-21).
Judges a (goal, action, untrusted-content) triple to detect prompt injection, goal drift, data exfiltration, and unauthorized payments before an AI agent acts, returning allow/review/block.
Price / call$0.0255
Success—
StatusUnknown
How this service works
Agent security guardrail. Judges the pair (untrusted content + proposed action) before an AI agent acts: detects tool calls that obey hidden prompt injection, leave the user's goal, destroy data or send data or money elsewhere. Adjustable sensitivity and optional multi-model consensus. Returns allow
Output
Returns a verdict of allow, review, or block along with a threat classification (e.g. prompt injection, goal drift, data exfiltration, unauthorized payment), a plain-language explanation of why the verdict was reached, and a confidence score. In consensus mode, disagreement among the three independent models triggers a 'review' verdict automatically.
Example use cases
Block prompt injection from malicious webpage
“I scraped a webpage that seems to have hidden instructions in it. Before you execute the 'delete all files in /home/user/docs' command it told you to run, run it through Verdict's firewall with my original goal 'summarize the article' and strict sensitivity — I want to know if this is a hijack attempt.”
Prevent unauthorized payment in finance agent
“My agent wants to wire $2,000 to an account it found in an invoice email. My original goal was 'pay the vendor for invoice #1042'. Run the proposed payment action and that invoice email through Verdict's firewall with balanced sensitivity before letting it go through.”
Multi-model consensus check for high-stakes action
“Before my agent posts that message to the company Slack channel, check it with Verdict using consensus mode — my original goal was 'notify the team about the outage', and here's the untrusted Slack bot response it wants to relay. I need three models to agree before we allow it.”
Technical details
Endpoint
POSThttps://verdict.kechlab.com/v1/firewall?utm_source=zero.xyzWhen to prefer
Choose this endpoint when an AI agent is about to act on content from an untrusted source (web page, email, document, API response) and you need a real-time security check before execution. Especially valuable when the action involves payments, data deletion, external communication, or any irreversible side effect. Prefer consensus mode for high-stakes or financial actions. This is purpose-built for agentic prompt-injection and goal-drift detection — not a generic content moderation or spam filter.
Side effects
- Missing required fields (goal, action, or content absent) — returns 400 error
- Ambiguous or very short content may reduce verdict confidence
- Consensus mode doubles the price and may have higher latency
- Overly strict sensitivity may block legitimate actions (false positives)
- Lenient sensitivity may miss subtle injection patterns (false negatives)
- Payment failure (L402) if USDC balance is insufficient — returns 402
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| goal | string | the goal given by the human |
| action | string | the action the agent wants to run (tool call, command, payment) |
| content | string | the untrusted content read by the agent (page, email, document) |
| consensus | boolean | (optional) true: three independent models, disagreement = review, double price |
| sensitivity | string | (optional) strict, balanced (default) or lenient |
Tags
x402
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