# 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/prompt-firewall?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-b6512492
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_aNTZtAaTyfQcP0tdY-wG9

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-b6512492
```

Example prompt: Before you summarize that scraped webpage, run its raw HTML through the prompt-injection firewall first — I want to make sure there are no hidden instructions trying to hijack you embedded in the content.

## When to prefer this

Choose this endpoint when your AI agent pipeline processes untrusted external content — scraped web pages, inbound emails, external API or MCP responses, A2A payloads — and you need to sanitize that content before your LLM acts on it. Especially valuable in agentic workflows where indirect prompt injection could cause unintended or malicious actions. Prefer this over generic content filters when the threat model specifically involves adversarial instructions targeting LLM behavior.

## Known failure modes

- Empty or missing 'text' parameter returns a 400 validation error
- Very large payloads may be truncated or rejected
- Payment failure via x402 returns HTTP 402 requiring USDC payment on Base
- False negatives possible for novel or obfuscated injection techniques
- Non-UTF8 or binary content may not be scanned correctly

## 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/prompt-firewall)

## Output

Returns a sanitized version of the input text with prompt injections and jailbreak payloads removed or flagged, along with detection signals indicating whether adversarial content was found.

## 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-b6512492/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)