# Codex

> How to connect ZoomInfo MCP to OpenAI Codex: install the ZoomInfo plugin for the hosted server plus our GTM skills, or add it manually as a Custom MCP entry.

**Date:** 2026-09-25  
**Source:** https://gtm.ai/docs/mcp/clients/codex

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## Overview

Codex is OpenAI's coding agent, powered by ChatGPT. ZoomInfo ships as a Codex plugin, so a single install gives Codex the hosted ZoomInfo MCP server and our GTM skills at once. If your Codex build doesn't expose plugins yet, add the MCP server by hand through the Custom MCP form. Both connect to the same endpoint and authenticate over OAuth.

## Setup

  **Open the Plugin Directory**

In the Codex app, open **Plugins**. In the CLI, run `codex` and then `/plugins` to open the plugin browser.

  **Find ZoomInfo**

Search for **ZoomInfo** and open its listing.

  **Install**

In the app, select **Add to Codex**. In the CLI, select **Install plugin**.

  **Connect your ZoomInfo account**

Codex prompts you to sign in with ZoomInfo the first time it uses the server. Use your normal credentials or SSO. There's no developer app to register and no OAuth callback to host.

  **Verify the connection**

Ask a question that needs ZoomInfo data, like *"How many employees does Snowflake have?"* The tool invocation appears inline.

**Next: run your first session.** Once ZoomInfo is connected, paste this into a new Codex session. It starts from your saved GTM context and asks before it spends credits:

## What the Plugin Adds

The plugin bundles the hosted MCP server at `https://mcp.zoominfo.com/mcp` plus a set of GTM skills, prewritten workflows that chain the underlying tools into finished output: account briefs, target lists, buying-committee maps, and lead scores. To run one explicitly, type `@` in the Codex prompt and pick the skill. Otherwise describe the outcome and Codex selects the skill that fits.

For the full skill list and a deeper walkthrough, see the [Codex setup guide](/guides/how-to-connect-to-zoominfo-mcp-in-codex).

## Prefer the Manual Route? Custom MCP

If your Codex build doesn't expose plugins, or you want the server without the bundled skills, add it through the Custom MCP form:

  **Open Codex Settings**

From inside Codex, go to **Settings**, then **Custom MCP**.

  **Add a new MCP server**

Click **Add** and fill in:

    - **Name:** `ZoomInfo`
    - **Transport:** **Streamable HTTP**
    - **URL:** `https://mcp.zoominfo.com/mcp`

  **Save and authenticate**

Click **Save**. Codex prompts you to sign in with ZoomInfo. Use your normal credentials or SSO.

## Troubleshooting

**You don't see ZoomInfo in the Plugin Directory:** the listing may not have reached your directory search yet. Fall back to the Custom MCP route above.

**Codex doesn't show a Custom MCP option:** your Codex plan or workspace may not have Custom MCP enabled. Check with your OpenAI admin or workspace owner.

**Authentication fails on sign-in:** confirm you're using your personal ZoomInfo credentials, not a shared or admin-only account.

**Codex doesn't see any ZoomInfo tools:** for the plugin, confirm it shows as installed and enabled in `/plugins`. For Custom MCP, confirm the entry is listed and the URL is exactly `https://mcp.zoominfo.com/mcp`.

**Credit errors on enrichment or research calls:** check which credits your account has. MCP can't draw from recurring monthly credits, which some older subscriptions carry; free accounts and bulk data credits work. See [Which credits MCP uses](/docs/mcp/credits#which-credits-mcp-uses).

## What's Next

For the full walkthrough including every GTM skill, see [How to Add ZoomInfo to Codex](/guides/how-to-connect-to-zoominfo-mcp-in-codex). For the same setup in Anthropic's CLI, see [Claude Code](/docs/mcp/clients/claude-code). For the full tool reference, see the [MCP Tools documentation](/docs/mcp/tools).