# 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 serp-extract.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 with prompt-injection firewall protection.

## Facts

- Endpoint: GET https://serp-extract.agentdiet.dev/v1/agent-tool-marketplace?utm_source=zero.xyz
- Price: $0.01/call
- Payment: MPP
- Status: unknown
- Last checked: 2026-10-21
- Activations on Zero: 0
- Provider: serp-extract.agentdiet.dev
- Website: https://serp-extract.agentdiet.dev
- Canonical page: https://www.zero.xyz/c/serp-extract-agentdiet-dev-universal-a2a-mcp-tool-discovery-safe-c0fb2541
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_TIlNPd-VjstM5RsCKOBs2

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 serp-extract-agentdiet-dev-universal-a2a-mcp-tool-discovery-safe-c0fb2541
```

Example prompt: Search the A2A and MCP tool marketplace for any servers or agent tools that can handle SEC filings and company enrichment — I want the best matches with compressed results.

## When to prefer this

Choose this endpoint when an AI agent needs to dynamically discover which MCP servers or A2A tools support a given capability at runtime, rather than hardcoding tool URLs. It is especially useful for swarm orchestrators, agent-builder pipelines, and meta-agents that need to route sub-tasks to the most appropriate specialized tool without maintaining a static registry.

## Known failure modes

- Empty or too-broad query returns low-relevance or no results
- Queried endpoint URL is unreachable or non-compliant, returning a validation error
- Payment not fulfilled (HTTP 402) when x402 micropayment header is absent or malformed
- Query string too short (minLength:1 not met) causes schema validation error
- Marketplace index may not reflect newly added MCP servers not yet crawled

## 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://serp-extract.agentdiet.dev/v1/agent-tool-marketplace)

## Output

Returns a list of matching MCP servers or A2A tools ranked by relevance to the query, with token-compressed metadata (85% compression), capability descriptions, endpoint URLs, and prompt-injection safety signals from the Prompt-Guard firewall.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "query"
 ],
 "properties": {
  "limit": {
   "type": "integer",
   "default": 20,
   "maximum": 100,
   "minimum": 1,
   "description": "Maximum number of items to return per page (1-100)"
  },
  "query": {
   "type": "string",
   "minLength": 1,
   "description": "Capability search query (e.g. 'context compression', 'github security', 'sec filings', 'company enrichment') or endpoint URL to verify"
  },
  "cursor": {
   "type": "string",
   "description": "Opaque pagination cursor for fetching the next page"
  }
 }
}
```

## Response schema (JSON Schema)

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

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/serp-extract-agentdiet-dev-universal-a2a-mcp-tool-discovery-safe-c0fb2541/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from serp-extract.agentdiet.dev](https://www.zero.xyz/host/serp-extract.agentdiet.dev/llms.txt)