Once connected, Codex can read and write Quadratic spreadsheets from inside a terminal session, from the Codex IDE extension, or from any app built on the Codex Agents SDK — all using the same config.

## How to add Quadratic MCP to Codex CLI

### Install Codex (if you haven’t already)

Install the Codex CLI with npm. If you already have codex on your PATH, skip this step.

```bash
npm install -g @openai/codex
```

### Run the Quadratic MCP install command

Paste the following into your terminal. Codex writes the configuration to `~/.codex/config.toml` so both the CLI and the IDE extension pick it up.

```bash
codex mcp add quadratic --url https://mcp.quadratichq.com/
```

### Authenticate inside Codex

Start Codex with `codex`. In the TUI, run `/mcp` to see registered servers. On first use Codex will open a browser window for the Quadratic OAuth flow. Approve access.

### Use Quadratic in Codex

Ask Codex to do something with your spreadsheets. For example: "In Quadratic, build a cohort retention analysis from the events sheet." Codex will invoke Quadratic MCP tools and work with the results alongside your code.

## Prefer editing config.toml?

Codex stores MCP configuration in `~/.codex/config.toml`. Merge the snippet below into the file to register Quadratic manually. You can also create a project-scoped config at `.codex/config.toml`.

```toml
[mcp_servers.quadratic]
url = "https://mcp.quadratichq.com/"
enabled = true
```

## Codex CLI + Quadratic MCP FAQs

### Does this work with the Codex IDE extension too?

Yes. The Codex CLI and the Codex IDE extension share `~/.codex/config.toml`, so once you add Quadratic in the CLI it’s instantly available in the extension as well.

### Where does Codex store my Quadratic OAuth token?

Tokens are stored in the credential store configured by `mcp_oauth_credentials_store` in config.toml. The default "auto" uses the OS keychain on macOS and Windows, and an encrypted file on Linux.

### How do I list or remove the Quadratic MCP server?

Run `codex mcp list` to see every configured server, `codex mcp get quadratic` for details, and `codex mcp remove quadratic` to remove it.

### Can I use Quadratic from the Codex Agents SDK?

Yes. Any agent built on the Codex Agents SDK or started with `codex mcp-server` can call Quadratic MCP tools — same config, same auth.

### What is the Quadratic MCP URL?

The Quadratic MCP server is hosted at `https://mcp.quadratichq.com/`. Paste this URL into your Codex CLI MCP configuration.

### Is Quadratic MCP free?

Yes. Quadratic MCP is included with every Quadratic plan, including the free tier. You only need a Quadratic account and a supported AI client.

### Is it secure?

Yes. Quadratic MCP uses OAuth 2.0 to authenticate each AI client with your Quadratic account. Your AI only sees files and data you already have access to, and you can revoke any connected client at any time in Quadratic settings.

### What can I do with Quadratic MCP in Codex CLI?

Once connected, Codex CLI can read values from your Quadratic sheets, write cells and formulas, run Python and SQL, and build charts. Ask Codex CLI any question about your spreadsheets the same way you’d ask about a PDF or URL.

### Which other AI clients support Quadratic MCP?

Cursor, VS Code, Claude, ChatGPT, and Windsurf all work with Quadratic MCP today, plus any other client that supports remote Streamable HTTP MCP servers. [See the full list](/content/ai/mcp/index.html).