Skip to content

Blog

How to find B2B leads and verified emails in Claude with MCP

Connect an MCP server to Claude, Claude Code, Cursor or ChatGPT, describe your ideal customer in plain words, and get a list with verified work emails.

All posts6 min read

Most prospecting tools make you think in filters: pick a job title from a dropdown, tick some industries, set a headcount range, then export and clean up in a spreadsheet. With an MCP server, you describe the people you want in a sentence and your AI assistant does the filtering, searching and list-building for you. This guide shows how to set that up in Claude, Claude Code, Cursor and ChatGPT, and how to keep the cost under control while you do.

What MCP is, in one paragraph

The Model Context Protocol (MCP) is an open standard, introduced by Anthropic in late 2024, that lets AI assistants call tools on other services. An MCP server publishes a set of tools ("search people", "find an email") with descriptions the model can read. When you ask for something, the assistant decides which tool to call, calls it and works with the result. Claude, Claude Code, Cursor, VS Code, Windsurf and many other apps now support MCP servers.

Why prospect from a chat

  • You describe the customer, not the filters. "Heads of RevOps at Series B SaaS companies in the UK" becomes titles, industries, headcount and country without you mapping it by hand.
  • Iterating is a sentence. Too many results? "Only companies with 50 to 200 people." Nobody found? The server suggests which filter to loosen, and the assistant tries again.
  • The research stays in one place. The same chat can search people, save them to a list, find verified emails and export a CSV, then help you write the first line of each email.

Set up the Leadscart MCP server

The server lives at https://leadscart.io/api/mcp and works on every plan, including Free. Pick your tool:

Claude (web, desktop and mobile)

  1. Open Claude's connectors page and click Add custom connector.
  2. Name it Leadscart and use the URL https://leadscart.io/api/mcp.
  3. Click Add, then Connect. Sign in to Leadscart and click Allow. Claude signs you in, so there is no API key to copy.

On a Team or Enterprise plan, a Claude owner adds the connector once for the organisation under Organization settings → Connectors.

Claude Code

Create an API key under Settings → API & MCP in Leadscart (keys start with lc_live_ and are shown once), then run:

Terminal
claude mcp add --transport http leadscart https://leadscart.io/api/mcp \
  --header "Authorization: Bearer lc_live_…"

Start Claude Code and type /mcp. Leadscart should show as connected.

Cursor, VS Code, Windsurf and other MCP clients

Add a server with transport HTTP (sometimes called Streamable HTTP), the URL https://leadscart.io/api/mcp, and one header: Authorization with the value Bearer lc_live_…. The docs quickstart has step-by-step boxes for each tool, including a one-click Cursor install.

ChatGPT

ChatGPT's connector setup has no field for an API key header, so it connects through a custom GPT with Actions instead. In the GPT editor, add an action, choose Import from URL and paste https://leadscart.io/api/v1/openapi.json?for=chatgpt, then set authentication to API Key, Bearer, with your key. This needs a paid ChatGPT plan. The docs walk through every box.

Your first session

Start a new chat and ask in plain words, for example:

Find 10 VP Sales at US fintechs with 50–200 employees

Here is what happens behind the scenes:

  1. people_search turns your request into filters and returns matching people: name, title, company, location and LinkedIn profile. Searching is free. If the search is too broad or finds nobody, the response includes suggested filters and the assistant refines it.
  2. list_create and list_add save the people you want to keep. Free. Anyone who has opted out of Leadscart is skipped automatically.
  3. email_find looks up verified work emails for up to 25 people per call. It costs 1 credit per person, and only when a verified address comes back.
  4. list_export returns the list as rows or a CSV for your sending tool. Free.

Good follow-ups once you have a list:

  • "Drop anyone at a company with more than 500 employees."
  • "Find verified emails for the first 20. Tell me the most it can cost first."
  • "Export the list as a CSV with emails."
  • "How many credits do I have left?"

Keeping the cost under control

An assistant that can spend money needs guardrails. These are built into the server:

  • Searching, saving and exporting are free. Only finding an email spends credits, at 1 per verified address. Misses cost nothing.
  • Every response reports what it spent and what's left, so the assistant can tell you after each step.
  • Email lookups are capped at 25 people per call, so one misunderstood request can't spend a whole balance.
  • Daily fair-use limits cap how many people a workspace can reveal per day, whoever holds the key.
  • Keys expire after 180 days and can be revoked at any time from Settings.

It also helps to tell the assistant your rule up front: "Always tell me the maximum cost and wait for my yes before finding emails."

Try it

New accounts get 25 free credits, and the MCP server is included on every plan, Free too. Connect it, ask for the people you actually sell to, and judge the results for yourself. If you'd rather work in a spreadsheet, here's how to find a work email that won't bounce without an AI assistant.