Codex
How to connect ZoomInfo MCP to OpenAI Codex: install the ZoomInfo plugin for the hosted server plus 14 GTM skills, or add it manually as a Custom MCP entry.
Rowan BaileySenior Director, ProductOverview
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 14 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.
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.
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: MCP requires bulk data credits. Confirm with your ZoomInfo admin that your account has bulk credits enabled, not recurring monthly credits.
What's Next
For the full walkthrough including every GTM skill, see How to Add ZoomInfo to Codex. For the same setup in Anthropic's CLI, see Claude Code. For the full tool reference, see the MCP Tools documentation.