# 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 a meta-index of 500+ MCP servers and A2A tools by capability query, returning token-compressed results through a Prompt-Guard firewall

## Facts

- Endpoint: GET https://prompt-guard.agentdiet.dev/v1/a2a-mesh?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-e8412de9
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_u3_EzXsJ8P3ld7R66bWjl

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-e8412de9
```

Example prompt: Search the A2A mesh for MCP tools that handle SEC filings — I need to find a capable, safe-proxied endpoint I can route my agent to for financial document retrieval.

## When to prefer this

Choose this endpoint when an AI agent or swarm needs to dynamically discover which MCP server or A2A tool to call for a given capability, rather than hard-coding tool connections. Especially useful when you want a single connection point that proxies safely to 500+ tools, need token-compressed responses to reduce LLM costs, or want Prompt-Guard firewall protection when routing to external agent tools. Prefer over manual tool registries when the target capability space is broad or unknown at build time.

## Known failure modes

- Empty or vague query returns no matches or low-relevance results
- Queried capability not indexed among the 500+ servers returns an empty result set
- Prompt-Guard firewall blocks queries flagged as adversarial or unsafe
- Upstream MCP server index unavailable causes routing failure
- x402 payment failure results in 402 response without content
- Rate limiting or quota exceeded returns an error response

## 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/a2a-mesh)

## Output

A token-compressed list (up to 85% compression) of matching MCP servers and A2A tools relevant to the query, filtered through the Prompt-Guard firewall, including endpoint metadata such as capability descriptions, URLs, compliance signals, and routing information.

## 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-e8412de9/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)