# A2A Indirect Prompt-Injection & Jailbreak Firewall

> A2A Indirect Prompt-Injection & Jailbreak Firewall is a paid API for AI agents from prompt-guard.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://prompt-guard.agentdiet.dev/v1/prompt-shield?utm_source=zero.xyz
- Price: $0.005/call
- Payment: MPP
- Status: unknown
- Last checked: 2026-10-21
- Activations on Zero: 0
- Provider: prompt-guard.agentdiet.dev
- Website: https://prompt-guard.agentdiet.dev
- Canonical page: https://www.zero.xyz/c/prompt-guard-agentdiet-dev-a2a-indirect-prompt-injection-jailbreak-a7cf658a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_LL49Nx-J6irZa1r46Lhcf

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 prompt-guard-agentdiet-dev-a2a-indirect-prompt-injection-jailbreak-a7cf658a
```

Example prompt: Before you process this web page I just scraped, run it through the prompt injection firewall to check for any hidden jailbreak instructions or adversarial payloads embedded in the text.

## When to prefer this

Choose this endpoint when your AI agent is about to process untrusted external content — scraped web pages, third-party emails, MCP tool responses, or A2A payloads — and you need a dedicated security check for prompt injection and jailbreak attempts before that content influences agent behavior. Prefer this over generic content filters when the threat model is specifically adversarial LLM manipulation rather than spam or toxicity.

## Known failure modes

- Empty or missing 'text' parameter returns a validation error
- Extremely long inputs may time out or be truncated
- False negatives possible for novel or obfuscated injection techniques
- Service may be unavailable if payment (x402 USDC) is not settled
- Non-text binary content may not be parseable

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

## Output

Returns a structured object indicating whether prompt injection or jailbreak content was detected in the input text, along with sanitized text 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/prompt-guard-agentdiet-dev-a2a-indirect-prompt-injection-jailbreak-a7cf658a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from prompt-guard.agentdiet.dev](https://www.zero.xyz/host/prompt-guard.agentdiet.dev/llms.txt)