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The Callingbox MCP server exposes the public /v1 API as Model Context Protocol tools. Point any MCP client at it with your API key and your agent can place phone calls and manage phone numbers through natural language.

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Connect your MCP client

  1. Create an API key in the dashboard under Keys.
  2. Add the server to your MCP client’s configuration:
{
  "mcpServers": {
    "callingbox-mcp": {
      "url": "https://<deployment-id>.deploy.mcp-use.com/mcp",
      "headers": {
        "Authorization": "Bearer sk_live_your_api_key_here"
      }
    }
  }
}
The Authorization header is required on every request — the MCP server is stateless and forwards your key to the Callingbox backend on each tool call.

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Tools

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Calls

ToolDescription
create_callPlace an outbound AI phone call. Returns the created call record immediately.
list_callsList calls for the authenticated organization.
get_callFetch a call by ID with status, transcript, result, and returns.
wait_for_callPoll an in-progress call until it reaches a terminal status.
make_call_and_waitPlace a call and return the final result in one shot. High-leverage for agents.

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Numbers

ToolDescription
list_numbersList phone numbers owned by your organization.
search_available_numbersSearch purchasable numbers by country, area code, and type.
purchase_numberBuy an available number.
Webhook endpoints can be managed via the dashboard or the public API.

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Build your own agent

Any MCP-compatible client library works. Here’s a minimal example using mcp-use and OpenAI: 
import { MCPClient, MCPAgent } from "mcp-use";
import { ChatOpenAI } from "@langchain/openai";

const client = MCPClient.fromDict({
  mcpServers: {
    callingbox: {
      url: "https://<deployment-id>.deploy.mcp-use.com/mcp",
      headers: { Authorization: `Bearer ${process.env.CALLINGBOX_API_KEY}` },
    },
  },
});

const agent = new MCPAgent({
  llm: new ChatOpenAI({ model: "gpt-4o" }),
  client,
  maxSteps: 10,
});

const result = await agent.run(
  "Call +14155551234, ask if they have reservations available for 4 people on Friday at 7pm, and extract the answer.",
);

console.log(result);
The agent will pick make_call_and_wait, pass the appropriate prompt and returns schema, and wait for the call to complete before returning.

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Running it yourself

The server is open source and lives in mcp/ inside the Callingbox monorepo. To deploy your own instance: 
cd mcp
npm install
npx mcp-use login
npm run deploy
See mcp/README.md for full instructions.