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How to Connect ZoomInfo to Claude Code Using MCP

Set up the ZoomInfo MCP server inside Claude Code using a developer app, the claude mcp add command, and an OAuth handshake on localhost.

Rowan BaileyRowan BaileySenior Director, Product··6 min read

Claude Code is Anthropic's CLI for agentic coding. If you work in the terminal, you can give it the same ZoomInfo tools that ship with Claude Desktop: search, enrichment, similar companies, intent, research. The setup is a little different from Claude Desktop because Claude Code doesn't have a connector marketplace. You register the ZoomInfo MCP server with a one-line command, then authenticate through a browser callback.

This guide walks through the full setup: creating an MCP app in the ZoomInfo Developer Portal, wiring it into Claude Code, and verifying the connection.

What You Need Before You Start

Claude Code installed. If you don't have it yet, follow Anthropic's install instructions↗. Any recent version supports MCP.

A ZoomInfo subscription with bulk data credits. Any ZoomInfo package qualifies, but your account must have bulk data credits enabled. Recurring monthly credits are not supported by MCP. Check with your ZoomInfo admin if you're unsure. See the full requirements.

Access to the ZoomInfo Developer Portal. You'll create an MCP app there to generate the client credentials Claude Code needs. If you can't sign in, your ZoomInfo admin can enable DevPortal access on your seat.

Port 8080 available on localhost. The OAuth callback runs on http://localhost:8080/callback during the initial handshake. If port 8080 is already in use, either free it or pick a different port and match it in the steps below.

Step-by-Step Setup

1. Create an MCP App in the Developer Portal

Go to developer.zoominfo.com↗ and click Create App in the top right. In the modal, select MCP App and fill in:

  • Application name: anything that helps you recognize it later (e.g. claude-code-local).
  • Authentication type: Authorization Code.
  • Redirect URI: http://localhost:8080/callback.

Click Create. Your app appears in the DevPortal table.

2. Copy Your Client Credentials

Open the app and copy the client_id and client_secret. Treat the secret like a password: paste it directly into the next command or stash it in a password manager. Do not commit it, log it, or leave it in plaintext on disk.

3. Register ZoomInfo with Claude Code

From your shell, run:

claude mcp add --transport http \
  --callback-port 8080 \
  --client-id <your-client-id> \
  --client-secret \
  zoominfo https://mcp.zoominfo.com/mcp

Replace <your-client-id> with the value from the DevPortal. The --client-secret flag with no value tells Claude Code to prompt for the secret interactively, so it's never stored in your shell history.

A few notes:

  • --transport http selects HTTP transport. ZoomInfo's MCP server does not use stdio.
  • --callback-port 8080 has to match the redirect URI you registered in step 1. Change both together if you need a different port.
  • zoominfo is the local name Claude Code will use to reference this server. Pick whatever name you want; the guide assumes zoominfo.

4. Initialize the Connection

Inside a Claude Code session, run:

/mcp

Claude Code opens your default browser to the ZoomInfo login page. Sign in with ZoomInfo credentials or SSO, wait for the redirect back to localhost, and watch the terminal for a confirmation that the zoominfo server is connected. Close the browser tab when you're done.

That's it. All ZoomInfo tools are now exposed to Claude Code.

Verifying the Connection Works

Try a question that needs ZoomInfo data:

How many employees does Snowflake have?

or:

Look up the CEO of Datadog.

If the connector is healthy, Claude Code calls the matching ZoomInfo tool and returns live data. You'll see the tool invocation and arguments inline. If Claude says it can't reach ZoomInfo, the server probably hasn't finished authenticating. Re-run /mcp and check the status output.

For a broader smoke test, chain tools together:

Find 5 cybersecurity companies in New York with 200-500 employees, then find the VP of Engineering at each one.

That exercises Lookup, Search Companies, and Search Contacts in sequence. To confirm intent data access:

Are any companies showing buying intent for "Data Integration" with a signal score above 80?

Working With Tools in Claude Code

Claude Code selects tools the same way Claude Desktop does: it reads the MCP tool descriptions and picks the right one for your request. You don't need to name the tool. But the CLI context has a few things worth knowing.

The /mcp command is your status panel. Run /mcp any time to see which servers are connected, which tools are exposed, and the current auth state. This is the fastest way to debug a broken connection.

Tool results land in your terminal context. Direct tools (Search, Enrich, Lookup) return data into Claude Code's context window. Large result sets eat context quickly, so narrow filters before running a search over thousands of companies.

Research tools run sub-agents. Account Research and Contact Research synthesize large payloads before returning a summary. They cost more credits per call, but they keep your context window manageable for work that spans multiple accounts.

Bulk credits apply the same way. Enrichment tools batch up to 25 records per call. Each record consumed counts against your bulk credits regardless of whether Claude Code or Claude Desktop made the call.

Troubleshooting

/mcp never opens the browser. Check that port 8080 is free. Run lsof -i :8080 to see what's holding it. If another process owns the port, either stop it or re-register with a different --callback-port. The redirect URI in your DevPortal app has to match the new port.

"Invalid client" or "redirect_uri mismatch" during auth. The redirect URI in your DevPortal app must match exactly: http://localhost:8080/callback, lowercase, no trailing slash. Mismatches here are the most common cause of a failed handshake.

Claude Code doesn't see any ZoomInfo tools. Run /mcp and confirm the zoominfo server shows as connected. If it's listed but shows an auth error, re-run the slash command to re-trigger the OAuth flow.

The connection stops working after a few hours. Your ZoomInfo session may have expired. Re-run /mcp to refresh tokens.

Credit errors on enrichment or research calls. MCP requires bulk data credits. Confirm with your ZoomInfo admin that your account has bulk credits enabled, not recurring monthly credits.

What's Next

With the connector live, Claude Code can pull account lists, enrich contacts, and prep deals in the same session you're writing code. For a deeper walkthrough of audience building, see How to Build Audiences and Lists Inside Claude. For the full tool reference, see the MCP Tools documentation.