NumberBroom MCP Server

A remote MCP server that lets AI agents (Claude Code, Cursor, Claude Desktop and other MCP clients that can send an Authorization header) verify US phone numbers through the NumberBroom API: carrier-level line type, carrier name, an activity score with a likely-disconnected flag, and TCPA litigator status.

This server is a thin, stateless proxy. It has no database and runs no OAuth flow — it forwards your NumberBroom API key straight through to https://numberbroom.com/api/v1, which already owns authentication, rate limiting, billing, and abuse protection. See numberbroom.com/developers for the underlying REST API this wraps.

Tools

Tool	Description	Cost
`verify_phone_number`	Line type, carrier, activity score, TCPA litigator flag for one US number.	$0.20/call, charged to your NumberBroom credit balance. Unparseable numbers are not charged.
`get_credit_balance`	Remaining pre-paid credit balance on your NumberBroom account.	Free.

Get an API key

Sign up at numberbroom.com and add credit to your account.
Generate an API key at numberbroom.com/settings.

Connect a client

Add this server as a remote MCP connection using its deployed URL, https://numberbroom.com/mcp, with your NumberBroom API key as a Bearer token in the Authorization header:

Code

Authorization: Bearer nb_live_YOUR_KEY

Step-by-step setup for Claude Code, Cursor, Claude Desktop, ChatGPT and other clients, with copy-paste config for each, is at numberbroom.com/mcp-server. Opening https://numberbroom.com/mcp in a browser redirects there; MCP clients are unaffected.

Local development

Terminal

npm install
npm run dev

This starts the server at http://localhost:8787/mcp via wrangler dev.

Deploy

Terminal

npm run deploy

Deploys to Cloudflare Workers as numberbroom-mcp. Requires a Cloudflare account authenticated via wrangler login.

Why a proxy, not a rewrite

Every tool call here is a direct, unmodified pass-through to NumberBroom's own /api/v1 endpoints. That means:

Auth, rate limiting (5,000 lookups per key per day at most, and 500 for calls through this server unless the key has its own limit set in Settings), the circuit breaker, and billing are all enforced exactly once, by NumberBroom's own API — this server does not duplicate or second-guess any of it.
A number that fails to parse costs nothing, same as calling the REST API directly.
An upstream error page or network failure comes back to the agent as a plain tool error, never a thrown exception.
This server never sees or stores your API key beyond the lifetime of a single request; each MCP tool call constructs an isolated server instance with no shared state between callers.

License

MIT