# 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 2026-10-21).

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

## Facts

- Endpoint: GET https://hn-pulse.agentdiet.dev/v1/llm-guard?utm_source=zero.xyz
- Price: $0.005/call
- Payment: MPP
- Status: unknown
- Last checked: 2026-10-21
- 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-c8465bf9
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_qUq8q_uluRNfjTnP58Pqn

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-c8465bf9
```

Example prompt: Before you process this scraped webpage content, run it through the prompt injection firewall to check for any hidden jailbreak instructions and give me the sanitized version: '<html>...page content here...</html>'

## When to prefer this

Choose this endpoint when your AI agent pipeline ingests content from untrusted external sources — web scraping, user-submitted text, third-party MCP tool responses, or A2A payloads — and you need to guard the LLM from indirect prompt injection or jailbreak hijacking before processing that content downstream. Prefer this over general content moderation tools when the threat model is specifically prompt injection and LLM manipulation rather than hate speech or NSFW filtering.

## Known failure modes

- Empty or missing 'text' parameter returns a validation error
- Extremely long payloads may exceed size limits or cause timeouts
- False negatives possible — novel or obfuscated injections may not be caught
- Service unavailability returns HTTP 402 or 5xx errors
- Highly encoded or multi-layer obfuscated injections may evade detection

## 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 an object indicating whether prompt injection or jailbreak content was detected in the input, along with a sanitized version of the text with malicious instructions removed or neutralized.

## 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-c8465bf9/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)