# 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/llm-guard?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-57c2b7db
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_TbBLTyckNNs47kBYc_LFA

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-57c2b7db
```

Example prompt: Before you summarize that webpage I just fetched, run its raw HTML through the prompt injection firewall to make sure there are no hidden instructions trying to hijack you.

## When to prefer this

Choose this endpoint when your AI agent pipeline ingests content from untrusted external sources — web pages, emails, third-party API responses, MCP tool outputs, or A2A agent messages — and you need to sanitize that content before passing it to an LLM. Prefer this over manual filtering when you need automated, scalable protection against indirect prompt injection and jailbreak attempts in agentic workflows.

## Known failure modes

- Empty or missing 'text' parameter returns a 400 validation error
- Extremely large payloads may be rejected or truncated
- Novel or obfuscated injection techniques may evade detection
- Non-text binary content may not be processed correctly
- Service unavailability returns 5xx errors
- Payment not completed via x402 returns 402 Payment Required

## 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/llm-guard)

## Output

Returns a sanitized version of the submitted text with 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/prompt-guard-agentdiet-dev-a2a-indirect-prompt-injection-jailbreak-57c2b7db/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)