# A2A Indirect Prompt-Injection & Jailbreak Firewall

> A2A Indirect Prompt-Injection & Jailbreak Firewall is a paid API for AI agents from defi-yield.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://defi-yield.agentdiet.dev/v1/prompt-shield?utm_source=zero.xyz
- Price: $0.005/call
- Payment: MPP
- Status: unknown
- Last checked: 2026-10-21
- Activations on Zero: 0
- Provider: defi-yield.agentdiet.dev
- Website: https://defi-yield.agentdiet.dev
- Canonical page: https://www.zero.xyz/c/defi-yield-agentdiet-dev-a2a-indirect-prompt-injection-jailbreak-5d164d15
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_32V6IbKia73SDXLOPFrcQ

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 defi-yield-agentdiet-dev-a2a-indirect-prompt-injection-jailbreak-5d164d15
```

Example prompt: Before you summarize that webpage I just fetched, run it through the prompt-injection firewall to make sure there are no hidden instructions embedded in it that could hijack your behavior.

## When to prefer this

Choose this endpoint when your AI agent or pipeline needs to safely process untrusted external content — such as scraped web pages, user-submitted text, emails, MCP tool responses, or A2A payloads — before passing them to an LLM. It is specifically designed for the indirect prompt injection threat model (content that tries to hijack agent behavior via malicious instructions hidden in data), making it ideal for agentic workflows that consume third-party or user-supplied content at runtime.

## Known failure modes

- Empty or missing 'text' parameter returns a validation error
- Extremely large payloads may be rejected or truncated
- False negatives are possible for novel or obfuscated injection techniques
- Service unavailability or HTTP 402 payment failure blocks scanning
- Highly encoded or multi-layer obfuscated injections may 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://defi-yield.agentdiet.dev/v1/prompt-shield)

## Output

Returns a structured JSON object indicating whether prompt injection or jailbreak content was detected in the input text, along with sanitized text with malicious instructions removed or flagged, enabling safe downstream processing by AI agents.

## 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/defi-yield-agentdiet-dev-a2a-indirect-prompt-injection-jailbreak-5d164d15/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from defi-yield.agentdiet.dev](https://www.zero.xyz/host/defi-yield.agentdiet.dev/llms.txt)