# A2A Indirect Prompt-Injection & Jailbreak Firewall

> A2A Indirect Prompt-Injection & Jailbreak Firewall is a paid API for AI agents from mcp-security.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-security.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: mcp-security.agentdiet.dev
- Website: https://mcp-security.agentdiet.dev
- Canonical page: https://www.zero.xyz/c/mcp-security-agentdiet-dev-a2a-indirect-prompt-injection-jailbreak-6a1f97c6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_fCx1S8CxMop5AfF5ylytL

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-security-agentdiet-dev-a2a-indirect-prompt-injection-jailbreak-6a1f97c6
```

Example prompt: Before you process this scraped webpage content, run it through the prompt-injection firewall first to make sure there are no hidden jailbreak instructions embedded in it: '<html>...page content here...</html>'

## When to prefer this

Choose this endpoint when your AI agent pipeline ingests untrusted external content — scraped web pages, user emails, third-party MCP/A2A tool responses, or LLM outputs from external models — and you need a lightweight, per-call firewall check before that content influences agent behavior. Prefer this over generic content moderation APIs when your specific threat model is prompt injection and jailbreak in agentic/LLM contexts rather than toxic language or CSAM.

## Known failure modes

- Empty or missing 'text' parameter returns a 400 validation error
- Extremely long payloads may be truncated or rejected
- Payment required (HTTP 402) if x402 micropayment header is not supplied or insufficient
- False negatives possible for novel or highly obfuscated injection techniques
- Non-UTF-8 or binary 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://mcp-security.agentdiet.dev/v1/prompt-shield)

## Output

Returns a JSON object containing the threat assessment of the submitted text, including whether prompt injection or jailbreak payloads were detected, and a sanitized version of the input text 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/mcp-security-agentdiet-dev-a2a-indirect-prompt-injection-jailbreak-6a1f97c6/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from mcp-security.agentdiet.dev](https://www.zero.xyz/host/mcp-security.agentdiet.dev/llms.txt)