# Universal A2A & MCP Tool Discovery, Safe-Proxy & Swarm Router

> Universal A2A & MCP Tool Discovery, Safe-Proxy & Swarm Router is a paid API for AI agents from prompt-guard.agentdiet.dev, paid per call via MPP, $0.01/call, status unknown (last checked 2026-10-21).

Searches and routes across 500+ indexed MCP servers and A2A tools via a single connection, with token compression and prompt injection firewall

## Facts

- Endpoint: GET https://prompt-guard.agentdiet.dev/v1/agent-router?utm_source=zero.xyz
- Price: $0.01/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-universal-a2a-mcp-tool-discovery-safe-8ec2fb6e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ZrH3jsIoJuyb75gygCBdQ

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-universal-a2a-mcp-tool-discovery-safe-8ec2fb6e
```

Example prompt: Search your MCP and A2A tool index for anything that handles 'SEC filings' or 'company enrichment' and tell me which tools are available and how to call them.

## When to prefer this

Choose this endpoint when an agent needs to dynamically discover which MCP server or A2A tool provides a specific capability at runtime, rather than hardcoding tool URLs. Especially useful for swarm architectures needing single-connection access to hundreds of tools, or when token budget is constrained and 85% compressed tool manifests are needed. Also appropriate when prompt injection safety is a concern and a firewall proxy is required.

## Known failure modes

- Empty or too-vague query returns low-relevance results
- Queried capability not indexed returns empty match set
- Prompt injection attempt blocked by Prompt-Guard firewall with rejection notice
- Rate limiting or payment failure (x402) returns 402 Payment Required
- Upstream MCP server temporarily unavailable may reduce result set

## How this service works

Single-connection meta-router indexing 500+ MCP servers & A2A tools with 85% token compression and Prompt-Guard firewall. (Live x402 v2, IETF MPP & MCP endpoint at https://prompt-guard.agentdiet.dev/v1/agent-router)

## Output

A list of matching MCP servers and A2A tools relevant to the query, with compressed descriptions (85% token reduction), endpoint URLs, capability summaries, and routing recommendations for integrating with the selected tool.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "query"
 ],
 "properties": {
  "query": {
   "type": "string",
   "minLength": 1,
   "description": "Capability search query (e.g. 'context compression', 'github security', 'sec filings', 'company enrichment') or endpoint URL to verify"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object"
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/prompt-guard-agentdiet-dev-universal-a2a-mcp-tool-discovery-safe-8ec2fb6e/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)