# 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/llm-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-02345d84
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_tH7mDjUS1XAdWDrSnkIXD

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-02345d84 -d '<json body>'
```

Example prompt: Before you process that web page I just scraped, run the raw HTML through the prompt-injection firewall and give me back the sanitized version — I don't want any hidden instructions hijacking you.

## When to prefer this

Choose this endpoint when your agent pipeline ingests content from untrusted external sources — scraped web pages, third-party API responses, emails, MCP tool outputs, or A2A payloads — and you need to detect and neutralize hidden prompt injections or jailbreak attempts before they reach your LLM. Prefer this over generic content filters when you specifically need protection against adversarial AI-targeting attacks rather than general toxicity or spam filtering.

## Known failure modes

- Empty or missing 'text' field returns a validation error
- Extremely large payloads may time out or be rejected
- Payment failure (HTTP 402) if x402 USDC payment is not attached or insufficient
- Malformed JSON body returns a 400 error
- Ambiguous or borderline injections may produce false negatives

## 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/llm-guard)

## Output

Returns a JSON object containing the scan result, which includes whether a prompt injection or jailbreak payload was detected and a sanitized version of the input text safe for downstream LLM 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-02345d84/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)