# 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 2026-10-23).

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

## Facts

- Endpoint: POST https://preflight.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: preflight.agentdiet.dev
- Website: https://preflight.agentdiet.dev
- Canonical page: https://www.zero.xyz/c/preflight-agentdiet-dev-a2a-indirect-prompt-injection-jailbreak-90f594da
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_aZN_rnkQCFJtb55wGz3NG

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-90f594da -d '<json body>'
```

Example prompt: Before you process this scraped web page, run it through the prompt-injection firewall to check for any hidden instructions or jailbreak payloads embedded in the content — here's the raw HTML: [paste content].

## When to prefer this

Choose this endpoint when your AI agent pipeline ingests untrusted external content — scraped web pages, emails, API responses, MCP tool outputs, or A2A payloads — and you need to screen for indirect prompt injection or jailbreak attempts before that content enters your LLM context. It is especially valuable in autonomous agent workflows where retrieved or tool-generated content could contain adversarial instructions designed to redirect agent behavior.

## Known failure modes

- Empty or missing 'text' field returns a validation error
- Extremely long inputs may time out or be truncated
- Obfuscated or encoded injections may evade detection
- Non-text binary content may not be correctly parsed
- Payment failure (HTTP 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/llm-guard)

## Output

Returns a JSON object containing the scan result for the submitted text, including whether prompt injection or jailbreak payloads were detected and a sanitized version of the input safe for use in LLM pipelines.

## 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-90f594da/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)