Agent Card and Discovery

The Agent Card is A2A's discovery entry point. Any agent that fetches it learns who Caoliao is, what it can do, where to call it and what comes back — no separate integration document required.

Three discovery URLs

URL	Purpose
https://a2a.objqr.com/.well-known/agent-card.json	Standard discovery path of the service
https://qr61.cn/.well-known/agent-card.json	The same card, on a code domain
https://qr71.cn/.well-known/agent-card.json	The same card, on a code domain

All three return the same card.

Serving it from the code domains is deliberate. An agent that scans a Caoliao code receives a link like https://qr71.cn/..., and can discover the A2A service from that domain's .well-known path without knowing a2a.objqr.com beforehand.

Tip: clients still on A2A 0.2.x probe the older /.well-known/agent.json. That path is kept and returns the same card.

What is on the card

{
  "protocolVersion": "0.3.0",
  "name": "草料二维码实体查询 Agent",
  "description": "...",
  "url": "https://a2a.objqr.com/a2a/jsonrpc",
  "preferredTransport": "JSONRPC",
  "version": "0.1.0",
  "documentationUrl": "https://a2a.objqr.com/ext/caoliao-entity/v2",
  "iconUrl": "https://static.clewm.net/cli/images/cli_logo_new.png",
  "provider": {
    "organization": "草料二维码 (cli.im)",
    "url": "https://cli.im"
  },
  "capabilities": {
    "streaming": false,
    "pushNotifications": false,
    "stateTransitionHistory": false,
    "extensions": [ "..." ]
  },
  "defaultInputModes": ["text/plain", "application/json"],
  "defaultOutputModes": ["application/json", "text/plain"],
  "skills": [ "..." ]
}

Field	Description
protocolVersion	Target A2A protocol version, currently 0.3.0
description	Bilingual (Chinese + English) capability description, for calling agents to decide whether to use this service
url	The single JSON-RPC endpoint clients post to
preferredTransport	Transport, JSONRPC
version	Version of this agent itself, unrelated to the protocol version
documentationUrl	Points at the read-only contract extension spec
capabilities	Which protocol capabilities are supported, and which extensions are declared
defaultInputModes	Accepted input types: plain text or JSON
defaultOutputModes	Returned output types: JSON or plain text
skills	Three read-only skills, see Skills

Note: the card's name and provider.organization are in Chinese (the name means "Caoliao QR Entity Query Agent"). The description on the card — and on each skill — is bilingual, so an English-speaking agent can rely on the English half for capability selection.

The card carries no security or securitySchemes fields. That is intentional: the service requires no authentication, and per the A2A specification omitting these fields signals exactly that.

All three capabilities booleans are false, meaning: no streaming responses, no push notifications, no state-transition history.

Each skill uses the same input and output modes as the top-level defaults, so per-skill modes are omitted rather than repeated.

The read-only contract extension

The card declares an extension that spells out what comes back and which boundaries apply:

{
  "uri": "https://a2a.objqr.com/ext/caoliao-entity/v2",
  "required": false,
  "params": {
    "profile": "read-only",
    "schemaUrl": "https://a2a.objqr.com/ext/caoliao-entity/v2/schema.json",
    "appliesTo": ["get_entity", "get_records", "list_actions"],
    "invocation": "explicit-datapart-only",
    "rules": {
      "readOnly": true,
      "publicOnly": true,
      "singleOrgView": true,
      "actionsExecutable": false
    }
  }
}

A2A currently has no per-skill output schema field, so Caoliao uses the official extension mechanism to fill that gap. The extension provides two things:

• Specification (human-readable): https://a2a.objqr.com/ext/caoliao-entity/v2
• JSON Schema (machine-readable): https://a2a.objqr.com/ext/caoliao-entity/v2/schema.json

The schema is generated from the backend's own type definitions, so it cannot drift from what the service actually returns.

required is false: clients that do not recognize the extension can ignore it and still call normally.

About GB/Z 185—2026

The card declares a second extension:

{
  "uri": "urn:gb-z-185:aip",
  "required": false,
  "params": {
    "standard": "GB/Z 185(所有部分)—2026",
    "alignment": "field-level",
    "descriptionUrl": "https://a2a.objqr.com/.well-known/aip-agent.json"
  }
}

Caoliao also publishes a description file conforming to GB/Z 185—2026 (Artificial Intelligence — Agent Interconnection, a Chinese national guiding technical document) at /.well-known/aip-agent.json.

This is a pointer, not a format conversion. The A2A card itself follows the A2A specification exactly — not one field was changed for the standard. Parties needing the national-standard description fetch it separately from descriptionUrl. It is likewise required: false, so clients that do not recognize it simply ignore it.

Next

• Skills — what each of the three skills does
• Task and Response — what you get back from a call