# X402-Broker SERP — Universal MCP/API/Agent Discovery Search

> X402-Broker SERP — Universal MCP/API/Agent Discovery Search is a paid API for AI agents from x402broker.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-22).

Searches and returns ranked results across 7,000+ live AI tools, MCP servers, x402 APIs, and A2A agents indexed by X402-Broker

## Facts

- Endpoint: GET https://x402broker.com/v1/serp?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-22
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-broker-serp-universal-mcp-api-agent-discovery-search-b0fd1883
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_3YLh2WVQ081L7tKJAyInv

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 x402-broker-serp-universal-mcp-api-agent-discovery-search-b0fd1883
```

Example prompt: Search the X402-Broker marketplace for live APIs or MCP servers that can do real-time cryptocurrency price lookups — show me the top results with their quality scores.

## When to prefer this

Use this endpoint when an AI agent needs to dynamically discover the best available tool, MCP server, or x402-compatible API for a given task at runtime — especially when the specific capability is not hardcoded and needs to be looked up from a large index. Prefer this over static tool registries when you want TDQS quality scoring, multi-protocol support (x402, L402, IETF MPP), and a single unified search across 7,000+ live endpoints.

## Known failure modes

- Missing required 'input' object returns validation error
- Invalid HTTP method enum value causes schema rejection
- Empty or too-broad query may return low-relevance results
- Payment of $0.01 USDC not fulfilled causes 402 response
- Service unavailability results in non-200 status

## How this service works

Universal B2A/A2A/MCP Meta-Router & Autonomous Tool Marketplace indexing 7,340+ live capabilities across x402 v2 (5-chain EVM USDC), IETF MPP, and L402 with TDQS quality scoring and zero-fee pass-through execution.

## Output

Returns a JSON object with a 'data' field containing ranked tool/API/agent listings matching the query, a 'status' field confirming success, and an 'roi_proof' object including a compression_ratio_pct showing how much of the indexed universe was distilled into the response.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "POST"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "query": {
       "type": "string"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "data": {},
  "status": "ok",
  "roi_proof": {
   "compression_ratio_pct": 91.4
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-broker-serp-universal-mcp-api-agent-discovery-search-b0fd1883/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402broker.com](https://www.zero.xyz/host/x402broker.com/llms.txt)