# A2A Indirect Prompt-Injection & Jailbreak Firewall

> A2A Indirect Prompt-Injection & Jailbreak Firewall is a paid API for AI agents from mcp-compiler.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://mcp-compiler.agentdiet.dev/v1/system-prompt-guard?utm_source=zero.xyz
- Price: $0.005/call
- Payment: MPP
- Status: unknown
- Last checked: 2026-10-21
- Activations on Zero: 0
- Provider: mcp-compiler.agentdiet.dev
- Website: https://mcp-compiler.agentdiet.dev
- Canonical page: https://www.zero.xyz/c/mcp-compiler-agentdiet-dev-a2a-indirect-prompt-injection-jailbreak-60e35891
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Hcdr9_WV8nKwBwuzz4Kp8

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 mcp-compiler-agentdiet-dev-a2a-indirect-prompt-injection-jailbreak-60e35891
```

Example prompt: Before you process that scraped webpage content, run it through the prompt-injection firewall first — I want to make sure there are no hidden jailbreak instructions embedded in the HTML trying to hijack you.

## When to prefer this

Choose this endpoint when your AI agent pipeline ingests untrusted external content — scraped web pages, inbound emails, third-party API responses, MCP server outputs, or A2A payloads — and you need to sanitize it before passing it to an LLM to prevent indirect prompt injection or jailbreak hijacking. Prefer it over generic content filters when the threat model is specifically adversarial prompt manipulation targeting AI agents.

## Known failure modes

- Empty or missing 'text' parameter returns a validation error
- Extremely long payloads may be truncated or rejected
- Obfuscated or novel injection techniques may evade detection
- Payment failure (402) if x402 micropayment is not properly configured
- Non-text binary content may not be parsed correctly

## 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://mcp-compiler.agentdiet.dev/v1/system-prompt-guard)

## Output

Returns a sanitized version of the input text with hidden prompt injections 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/mcp-compiler-agentdiet-dev-a2a-indirect-prompt-injection-jailbreak-60e35891/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from mcp-compiler.agentdiet.dev](https://www.zero.xyz/host/mcp-compiler.agentdiet.dev/llms.txt)