Overview
Caoliao provides three entry points for agents: two MCP servers and one A2A service.
Two distinctions are all you need:
- Whether authentication is involved decides what data you read — Public MCP and A2A need no authentication and read a code's public content; Open Platform MCP requires authorization (OAuth or an API Key) and reads your organization's data.
- Who is calling decides between MCP and A2A — an MCP client you configure (Cursor, Claude Desktop, or your own agent) uses MCP; an agent you do not configure, which discovers services over the protocol itself, uses A2A.
| Public MCP | Open Platform MCP | A2A | |
|---|---|---|---|
| Endpoint | https://mcp.objqr.com/mcp | https://open.cli.im/mcp | https://a2a.objqr.com |
| Authentication | None | OAuth (beta) / API Key | None |
| Data | Public content of a code | Your organization's data | Public content of a code |
| Writes | Read only | Read only | Read only |
| Caller | MCP clients you configure | MCP clients / systems you configure | Agents speaking A2A |
How to choose
Choose by what you are building:
- Let an agent understand a Caoliao QR code — answer "what equipment is this, what state is it in, what has happened to it" after a scan → Public MCP. No account needed; set one URL and it works.
- Analyze Caoliao data inside office AI platforms such as WorkBuddy or QwenWork — let the AI compute metrics, summarize anomalies, build report pages → Open Platform MCP via OAuth authorization (beta), no Key needed; see the platform guides.
- Bring Caoliao data into your own systems or analysis pipelines — query metrics, read form structures, drill down to records → Open Platform MCP. It uses the same API Key as OpenAPI V2.
- The caller is not in your MCP configuration — any agent that speaks A2A can discover and call Caoliao from a scanned code → A2A.
Tip: the two MCP servers do not conflict — use both. One understands any single code; the other operates on your organization's data.
Discovery
Public MCP and A2A require no pre-arranged integration handshake — an agent can find them from a code itself:
- The code domains (
qr61.cn,qr71.cn) serve/.well-known/agent-card.json, which points to the A2A service - The
entity_getresponse of Public MCP (the ObjectCard — Caoliao's structured JSON description of the thing behind a code) carries anendpointsfield listing where this entity is reachable over MCP and A2A
In other words, scanning any Caoliao code is enough to discover both entry points. Open Platform MCP is the opposite by design — it is bound to your organization: with OAuth you sign in and confirm on the authorization page; with an API Key the credential comes from Authentication (OpenAPI V2). Its endpoint is fixed at https://open.cli.im/mcp.
Boundaries
- None of the three works across organizations: one call reads one organization's data.
- Public read scope = what anyone sees by scanning the code.
- All three entry points are currently read-only; for writes (adding records, verifying certificates) use the OpenAPI V2 REST API.