# A2A v0.3.0 Agent Card Manifest Endpoint

> A2A v0.3.0 Agent Card Manifest Endpoint is a paid API for AI agents from assay.agentdiet.dev, paid per call via MPP, $0.005000/call, status unknown (last checked 2026-10-23).

Returns the canonical A2A v0.3.0 Agent Card JSON manifest for a target A2A/MCP/x402 endpoint, including its grade, score, and status.

## Facts

- Endpoint: GET https://assay.agentdiet.dev/.well-known/agent-card.json?utm_source=zero.xyz
- Price: $0.005000/call
- Payment: MPP
- Status: unknown
- Last checked: 2026-10-23
- Activations on Zero: 0
- Provider: assay.agentdiet.dev
- Website: https://assay.agentdiet.dev
- Canonical page: https://www.zero.xyz/c/assay-agentdiet-dev-a2a-v0-3-0-agent-card-manifest-endpoint-7f310871
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Te_ERC4yh8S-FCJ5h-tIV

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 assay-agentdiet-dev-a2a-v0-3-0-agent-card-manifest-endpoint-7f310871
```

Example prompt: Can you fetch the canonical A2A v0.3.0 agent card manifest for https://agentdiet.dev and tell me its grade and score?

## When to prefer this

Use this endpoint when you need to programmatically retrieve the canonical A2A v0.3.0 Agent Card manifest for any A2A, MCP, or x402 endpoint — especially when you need a structured grade and score to evaluate protocol conformance before integration. Prefer this over manual inspection when automating agent discovery pipelines or vetting third-party services at scale.

## Known failure modes

- Target URL is unreachable or returns non-200 — status field reflects failure
- Invalid or malformed target URL parameter — likely 400 error
- Target endpoint does not implement A2A v0.3.0 — grade may reflect non-conformance
- Pagination cursor is invalid or expired — empty or error response
- Rate limiting or payment failure for the $0.005 per-call fee — 402 Payment Required

## How this service works

Return canonical A2A v0.3.0 Agent Card manifest (Live x402 v2, IETF MPP & MCP endpoint at https://assay.agentdiet.dev)

## Output

Returns a JSON object containing the agent card manifest for the target endpoint, including a status string, an alphanumeric grade (e.g. A, B, C), an integer score, the target URL, and optional pagination fields (has_more, next_cursor) for paginated audit records.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "target"
 ],
 "properties": {
  "target": {
   "type": "string",
   "default": "https://agentdiet.dev"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "status",
  "grade",
  "score"
 ],
 "properties": {
  "grade": {
   "type": "string"
  },
  "score": {
   "type": "integer"
  },
  "status": {
   "type": "string"
  },
  "target": {
   "type": "string"
  },
  "has_more": {
   "type": "boolean"
  },
  "next_cursor": {
   "type": "string",
   "nullable": true
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/assay-agentdiet-dev-a2a-v0-3-0-agent-card-manifest-endpoint-7f310871/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from assay.agentdiet.dev](https://www.zero.xyz/host/assay.agentdiet.dev/llms.txt)