# 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/tool-poisoning-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-9b668e1e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_b09wjmv6Rj9Wxa0LcltIo

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-9b668e1e
```

Example prompt: Before you process that scraped web page, run its content through the prompt-injection firewall and give me the sanitized version — I want to make sure there are no hidden jailbreak instructions embedded in it.

## When to prefer this

Choose this endpoint when your AI agent is about to process any untrusted external content — web pages, tool outputs, MCP responses, A2A payloads, or emails — and you need to verify it is free of hidden prompt injections or jailbreak instructions before it reaches your LLM. Particularly valuable in agentic pipelines where tool outputs are automatically fed back into the model without human review.

## Known failure modes

- Empty or missing 'text' parameter returns a validation error
- Very large payloads may time out or exceed input size limits
- Sophisticated obfuscated injections may evade detection (false negatives)
- Payment failure via x402 returns HTTP 402 blocking access
- Service unavailability returns 5xx with no sanitized output

## 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/tool-poisoning-shield)

## Output

Returns a structured object indicating whether prompt injection or jailbreak payloads were detected in the submitted text, along with a sanitized version of the input 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-9b668e1e/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)