# 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 to 500+ MCP servers and A2A agent tools via a single connection, with token compression and prompt injection firewall.

## Facts

- Endpoint: GET https://prompt-guard.agentdiet.dev/v1/universal-mcp-gateway?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-6e863c9e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_gXRKDnjp0UGlJgjLTOTCL

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-6e863c9e
```

Example prompt: Search the MCP tool index for 'SEC filings' and tell me which agent tools or servers are available to handle that capability.

## When to prefer this

Choose this endpoint when an agent needs to dynamically discover which MCP server or A2A tool can handle a specific capability at runtime, rather than hardcoding a specific tool. Ideal for swarm orchestration, multi-agent pipelines, or when the right downstream tool is unknown ahead of time. The built-in prompt firewall makes it safer than calling unknown MCP servers directly.

## Known failure modes

- Empty results if query is too vague or no tools match
- HTTP 402 payment required if x402 credentials are missing or insufficient
- Query string missing or empty returns validation error
- Upstream MCP servers unavailable may return partial or stale results
- Prompt injection attempts blocked by Prompt-Guard firewall with rejection notice

## 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/universal-mcp-gateway)

## Output

Returns a list of matching MCP servers or A2A tool endpoints relevant to the search query, with compressed metadata describing each tool's capabilities, likely including endpoint URLs, supported methods, and relevance scores. Compressed output aims for 85% token reduction versus full schema responses.

## 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-6e863c9e/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)