# A2A Indirect Prompt-Injection & Jailbreak Firewall

> A2A Indirect Prompt-Injection & Jailbreak Firewall is a paid API for AI agents from hn-pulse.agentdiet.dev, paid per call via MPP, $0.005/call, status unknown (last checked 2026-10-23).

Scans untrusted text, HTML, emails, MCP responses, or A2A payloads for hidden prompt injections and jailbreak attempts, returning sanitized output.

## Facts

- Endpoint: POST https://hn-pulse.agentdiet.dev/v1/guard?utm_source=zero.xyz
- Price: $0.005/call
- Payment: MPP
- Status: unknown
- Last checked: 2026-10-23
- Activations on Zero: 0
- Provider: hn-pulse.agentdiet.dev
- Website: https://hn-pulse.agentdiet.dev
- Canonical page: https://www.zero.xyz/c/hn-pulse-agentdiet-dev-a2a-indirect-prompt-injection-jailbreak-firewall-057638a5
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_W2fM5TdTSoqyYEmUyfHkQ

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability hn-pulse-agentdiet-dev-a2a-indirect-prompt-injection-jailbreak-firewall-057638a5 -d '<json body>'
```

Example prompt: Before you summarize that webpage, run its raw HTML through the prompt-injection firewall to make sure there are no hidden instructions trying to hijack you.

## When to prefer this

Choose this endpoint when your agent pipeline ingests content from untrusted external sources — scraped web pages, inbound emails, third-party tool responses, or A2A payloads — and you need a dedicated security layer to detect and neutralize hidden prompt injections or jailbreak attempts before the content reaches your LLM. Prefer it over generic content filters when the specific threat model is adversarial AI manipulation rather than spam or toxicity.

## Known failure modes

- Empty or missing 'text' field returns a 400 validation error
- Extremely long payloads may hit size limits or timeout
- Sophisticated obfuscated injections may evade detection (false negatives)
- Service unavailability returns 5xx; idempotency key allows safe retry
- Payment not settled returns HTTP 402 requiring x402 micropayment flow

## How this service works

Scans untrusted web pages, emails, MCP responses, or A2A payloads for hidden prompt injections and returns sanitized text. (Live x402 v2, IETF MPP & MCP endpoint at https://hn-pulse.agentdiet.dev/v1/guard)

## Output

Returns a JSON object indicating whether prompt injection or jailbreak content was detected, along with sanitized text safe for downstream agent consumption.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "text"
 ],
 "properties": {
  "text": {
   "type": "string",
   "minLength": 1,
   "description": "Untrusted text, HTML, or tool output to scan for hidden prompt injection or jailbreak payloads"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object"
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/hn-pulse-agentdiet-dev-a2a-indirect-prompt-injection-jailbreak-firewall-057638a5/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from hn-pulse.agentdiet.dev](https://www.zero.xyz/host/hn-pulse.agentdiet.dev/llms.txt)