# A2A Indirect Prompt-Injection & Jailbreak Firewall

> A2A Indirect Prompt-Injection & Jailbreak Firewall is a paid API for AI agents from preflight.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://preflight.agentdiet.dev/v1/prompt-guard?utm_source=zero.xyz
- Price: $0.005/call
- Payment: MPP
- Status: unknown
- Last checked: 2026-10-21
- Activations on Zero: 0
- Provider: preflight.agentdiet.dev
- Website: https://preflight.agentdiet.dev
- Canonical page: https://www.zero.xyz/c/preflight-agentdiet-dev-a2a-indirect-prompt-injection-jailbreak-5b5b7e27
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_uTf6KW0xjv6JmqAdjD_6B

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 preflight-agentdiet-dev-a2a-indirect-prompt-injection-jailbreak-5b5b7e27
```

Example prompt: Before you summarize this email I just received, scan it for any hidden prompt injections or jailbreak instructions embedded in the text — I don't trust the sender.

## When to prefer this

Use this endpoint whenever your AI agent consumes untrusted external content — scraped web pages, third-party API responses, MCP tool outputs, emails, or A2A messages — before passing that content to an LLM for processing. Prefer this over manual filtering when you need a dedicated, purpose-built firewall that specifically targets indirect prompt injection and jailbreak vectors rather than generic content moderation.

## Known failure modes

- Empty or missing 'text' parameter returns validation error
- Extremely long payloads may be truncated or rejected
- False negatives possible for novel or obfuscated injection techniques
- Non-text binary content may not be correctly parsed
- Network timeout on large HTML documents
- Payment failure (402) if x402 USDC balance is insufficient

## 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://preflight.agentdiet.dev/v1/prompt-guard)

## Output

Returns a structured object indicating whether prompt injection or jailbreak payloads were detected in the submitted text, along with a sanitized version of the content 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/preflight-agentdiet-dev-a2a-indirect-prompt-injection-jailbreak-5b5b7e27/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from preflight.agentdiet.dev](https://www.zero.xyz/host/preflight.agentdiet.dev/llms.txt)