# 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 2026-10-23).

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

## Facts

- Endpoint: POST https://prompt-guard.agentdiet.dev/paid?utm_source=zero.xyz
- Price: $0.005/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-53d77afe
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_HCmIPfV_xkVY4LLGx7b61

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-53d77afe -d '<json body>'
```

Example prompt: Before you process this webpage content, scan it for any hidden prompt injections or jailbreak attempts and give me the sanitized version I can safely pass to the next agent step.

## When to prefer this

Choose this endpoint when your AI agent pipeline ingests content from untrusted external sources — web pages, emails, third-party APIs, MCP tool responses, or A2A payloads — and you need to sanitize that content before it reaches your core LLM. Especially valuable in agentic workflows where indirect prompt injection is a real attack vector and you need a dedicated firewall step rather than relying on the LLM's own resistance.

## Known failure modes

- Empty or missing 'text' field returns a 422 validation error
- Extremely large payloads may time out or be rejected
- Payment failure via x402 returns HTTP 402 with payment instructions
- Obfuscated or novel injection techniques may evade detection
- Non-UTF-8 encoded content may cause parsing errors

## 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/paid)

## Output

Returns a JSON object containing the sanitized version of the input text with hidden prompt injections and jailbreak payloads removed or flagged, enabling safe downstream use in AI agent 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/prompt-guard-agentdiet-dev-a2a-indirect-prompt-injection-jailbreak-53d77afe/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)