Free API + MCP server, no key

Build with the front desk.

Three endpoints straight from Lobby's production receptionist stack. AI phone scripts in English and Mexican Spanish, voice agent agent system prompts, and missed-call math. Plain HTTPS, no key, no signup. And an MCP server, so your AI agents can call all of it as tools.

Quickstart

One curl. No auth.

Write a phone script

curl -X POST https://lobbyvoices.com/api/v1/phone-script \
  -H 'content-type: application/json' \
  -d {"mode":"voicemail","business":"Vargas Plumbing","trade":"plumbing","langs":["en","es"]}

Generate an voice agent agent prompt

curl -X POST https://lobbyvoices.com/api/v1/agent-prompt \
  -H 'content-type: application/json' \
  -d {"biz":"Vargas Plumbing","industry":"plumbing","tasks":["book","faqs"],"hours":"Mon-Sat 8am-6pm","spanish":true,"tone":"warm"}

Price a missed-call problem

curl -X POST https://lobbyvoices.com/api/v1/missed-call-cost \
  -H 'content-type: application/json' \
  -d {"callsPerWeek":75,"missedRatePct":33,"avgJobValue":380}

Endpoints

Three endpoints, zero ceremony.

POST/api/v1/phone-scriptAI writes a greeting, voicemail, on-hold message, or jingle lines. English, Spanish, or both.

POST/api/v1/agent-promptA production-grade system prompt for an voice agent agent: identity, booking flow, guardrails, escalation.

POST/api/v1/missed-call-costMonthly and yearly revenue lost to missed calls, plus recovery math and break-even.

Machine-readable spec: /api/v1/openapi.json

MCP

Give your agent the toolkit.

Connect the MCP server and your agent can write phone scripts, generate voice agent prompts, and price missed calls on its own, same endpoints, no key.

Claude Code

claude mcp add --transport http lobbyvoices https://lobbyvoices.com/api/mcp

Cursor · Claude Desktop · any MCP client

{
  "mcpServers": {
    "lobbyvoices": { "url": "https://lobbyvoices.com/api/mcp" }
  }
}

Tools your agent gets

write_phone_scriptGreeting, voicemail, on-hold, or jingle copy in EN, es-MX, or both.

write_ivr_menuA complete IVR phone-menu script. Greeting, numbered options, Spanish switch, operator line.

generate_voice_agent_promptA complete receptionist system prompt for voice agent agents.

simulate_receptionist_callRole-play a call against the real receptionist engine. Transcript, outcome, automatic EN/ES switch.

get_demo_call_numberThe live demo line a human can call right now, with suggested scripts in both languages.

calculate_missed_call_costThe leak, the recovery, and the break-even, as structured numbers.

should_i_hire_a_receptionistA coverage verdict with archetype, yearly leak, break-even and ROI.

save_my_receptionistSaves what you built for a real business and emails it over, with consent — plus the demo number and a signup link.

Fair use

Free, within reason.

No key, no signup. AI-backed endpoints are limited to 2 requests a minute per IP; the math and template endpoints are generous. Hard input caps keep the service healthy. Building something bigger on top of it? Tell us, we like builders. Contact us

The next step

The API is free. The receptionist answers for you.

Lobby is the AI front desk behind these endpoints, it answers every call, books the job, and speaks English and Spanish, 24/7.

Meet your receptionist