# A2A Agent Card Preflight Validator

> A2A Agent Card Preflight Validator is a paid API for AI agents from nohands-coinbase-bazaar.bytoken2023.workers.dev, paid per call via x402, $0.02/call, status unknown (last checked 2026-11-02).

Discovers and validates a public A2A Agent Card including its skills, provider, authentication, endpoint consistency, and unsafe URL detection before an agent interacts with it.

## Facts

- Endpoint: GET https://nohands-coinbase-bazaar.bytoken2023.workers.dev/v1/x402/agent/a2a-card-preflight?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-11-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/a2a-agent-card-preflight-validator-60737f71
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_o2a-RPJ2y4wNUoGkxJMnE

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 a2a-agent-card-preflight-validator-60737f71
```

Example prompt: Before I connect to this A2A agent at https://some-agent.example.com/.well-known/agent.json, can you run a preflight check on its agent card — verify its skills, provider, authentication setup, endpoint consistency, and flag any unsafe URLs?

## When to prefer this

Use this endpoint when your agent is about to interact with, pay, or integrate an unknown A2A agent and needs to validate its agent card before proceeding. Prefer this over generic HTTP inspection tools when you need A2A-specific checks like skill declarations, provider identity, and authentication consistency — not just raw HTTP metadata.

## Known failure modes

- Agent Card URL is not publicly reachable — returns connectivity error
- URL does not serve a valid A2A Agent Card JSON — returns parse/format error
- Agent Card fails endpoint consistency checks — flagged in report
- Unsafe URLs detected in card — flagged with details
- Authentication scheme is missing or malformed — noted in report
- Rate limiting or payment failure for the $0.02 USDC call

## How this service works

Discover and validate a public A2A Agent Card, its skills, provider, authentication, endpoint consistency, and unsafe URLs.

## Output

A structured preflight report covering the A2A Agent Card's validity, declared skills, provider identity, authentication scheme, endpoint consistency assessment, and a list of any unsafe or suspicious URLs found in the card.

## 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"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "url"
     ],
     "properties": {
      "url": {
       "type": "string",
       "example": "https://base-agent-preflight.bytoken2023.workers.dev",
       "pattern": "^https?://",
       "maxLength": 2048,
       "description": "Public agent origin or direct Agent Card URL."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "x-schema-family": "STRUCTURED_PRODUCT_RESULT",
     "x-schema-authority": "STRUCTURED_PRODUCT_RESULT",
     "additionalProperties": true
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/a2a-agent-card-preflight-validator-60737f71/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from nohands-coinbase-bazaar.bytoken2023.workers.dev](https://www.zero.xyz/host/nohands-coinbase-bazaar.bytoken2023.workers.dev/llms.txt)