# 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, $0.005000/call, status unknown (last checked 2026-10-23).

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

## Facts

- Endpoint: POST https://prompt-guard.agentdiet.dev/a2a?utm_source=zero.xyz
- Price: $0.005000/call
- Payment: MPP
- Status: unknown
- Last checked: 2026-10-23
- 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-fa43569d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Zfn0GVAkjlaJnnnX-x-Ry

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-fa43569d -d '<json body>'
```

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

## When to prefer this

Choose this endpoint when your AI agent pipeline processes untrusted external content — web pages, emails, tool responses, or third-party A2A payloads — before passing that content to an LLM or downstream agent. Especially valuable in multi-agent architectures where one agent receives data from another untrusted agent or external MCP server. Prefer this over generic content filters when you specifically need protection against prompt injection and jailbreak attacks in agentic workflows.

## Known failure modes

- Empty or missing 'text' field returns a 400 validation error
- Extremely large payloads may hit size limits or timeout
- Subtle or novel injection patterns may not be detected (false negatives)
- Service unavailability or payment failure (HTTP 402) if USDC balance is insufficient
- Obfuscated HTML or encoded injections may partially 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://prompt-guard.agentdiet.dev/a2a)

## Output

Returns a sanitized version of the input text with prompt injection and jailbreak payloads removed or flagged, along with detection metadata indicating whether malicious 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/prompt-guard-agentdiet-dev-a2a-indirect-prompt-injection-jailbreak-fa43569d/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)