# X402-BROKER Catalog Endpoint — MCP/A2A/x402 API Discovery

> X402-BROKER Catalog Endpoint — MCP/A2A/x402 API Discovery is a paid API for AI agents from mcp-gateway.agentdiet.dev, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-22).

Returns a searchable catalog of 31,390+ MCP servers, x402 APIs, and A2A agents available for brokered execution, settable in USDC on Base.

## Facts

- Endpoint: GET https://mcp-gateway.agentdiet.dev/v1/broker/catalog?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-catalog-endpoint-mcp-a2a-x402-api-discovery-4b6e7f7b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_yhosoHUnHjy_gOH3JoQe0

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-catalog-endpoint-mcp-a2a-x402-api-discovery-4b6e7f7b
```

Example prompt: Search the X402-BROKER catalog for MCP servers or x402 APIs related to 'weather forecasting' so I can find one to call from my agent pipeline.

## When to prefer this

Choose this endpoint when an AI agent needs to dynamically discover which MCP servers, x402 APIs, or A2A agents are available for a given task before routing execution. It is particularly useful in agentic pipelines that need to self-select tools at runtime, or when building agent orchestration layers that need a live, searchable registry of 30,000+ services accessible via USDC micropayments on Base.

## Known failure modes

- Payment not included or insufficient USDC (HTTP 402) — request rejected without valid x402 payment header
- Invalid query parameter type — 400 error if queryParams.query is not a string
- Method not in allowed enum (GET/POST) — validation failure
- Gateway unavailable or catalog service down — 503 or timeout
- Empty result set if query string matches no catalog entries

## How this service works

Deterministic B2A/A2A/MCP/x402/MPP/L402 execution and intelligence node at https://mcp-gateway.agentdiet.dev settling in USDC on Base.

## Output

Returns a JSON object with a 'data' field containing catalog entries for MCP servers, x402 APIs, and A2A agents, a 'status' field ('ok'), and an 'roi_proof' object showing a compression ratio (e.g. 91.4%) indicating the efficiency of the catalog 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-catalog-endpoint-mcp-a2a-x402-api-discovery-4b6e7f7b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from mcp-gateway.agentdiet.dev](https://www.zero.xyz/host/mcp-gateway.agentdiet.dev/llms.txt)