Call a door

Two packages for an agent that visits a company. @conciergeprotocol/client is the library. @conciergeprotocol/mcp is that library behind three tools, so Claude, Cursor, and other MCP hosts can ask a company.

The company publishes agent.txt. These packages call it. Source is at github.com/conciergeprotocol/js. Both are Apache 2.0. Node.js 18 or newer.

Client

Shell

npm install @conciergeprotocol/client

JavaScript

import { createClient } from '@conciergeprotocol/client'

const cap = createClient({ from: 'agent:my-assistant' })

const answer = await cap.ask('cosmicjs.com', 'Do you have a free plan?')
console.log(answer.reply)

from is agent: plus 1 to 64 letters, numbers, dots, underscores, or hyphens. It names the caller.

A follow-up sends only the new question. The company keeps the earlier turns.

JavaScript

const thread = cap.thread('cosmicjs.com')
await thread.ask('What is Cosmic?')
const price = await thread.ask('How much is the cheapest paid plan?')

discover returns null when a site has no front door. ask throws NoDoorError for the same case, which is the signal to browse the site instead.

ask waits up to two minutes. If the company is still answering, the message comes back with status: 'working' and no reply. Read it again with get. Do not write a reply while the status is working.

MCP

Install the server, or run it with npx. Cursor, Claude Desktop, and VS Code use the same block. In VS Code it goes in .vscode/mcp.json. In Cursor and Claude Desktop it goes in the MCP settings file.

Shell

npm install @conciergeprotocol/mcp

JSON

{
  "mcpServers": {
    "cap": {
      "command": "npx",
      "args": ["-y", "@conciergeprotocol/mcp"],
      "env": { "CAP_FROM": "agent:my-assistant" }
    }
  }
}

CAP_FROM names the caller. When it is unset, the server uses agent:cap-mcp. Hosts can also find the server in the MCP registry as io.github.conciergeprotocol/mcp.

Tool	What it does
`cap_discover`	Reads `agent.txt` and reports whether the domain has a front door.
`cap_ask`	Sends one question and waits up to 60 seconds.
`cap_check`	Reads a message that was still `working`.

cap_ask sends only the new question. Pass the previous message id for a follow-up. If the company is still answering, the tool returns the message id and no reply. Call cap_check.