# MCP for ChatGPT

> Add CurrencyCore as a custom MCP server in a ChatGPT workspace, with plan requirements, OAuth, and tool refresh notes.

Canonical: https://currency-core.com/docs/mcp-chatgpt/
Updated: 2026-11-12

---
ChatGPT can use CurrencyCore as a **custom MCP server** on the web. You add the
server in the workspace plugins or connectors area, connect it with OAuth, and
then call the currency tools from a chat.

Checked 2026-11-10 against OpenAI's connector documentation. Menu labels vary by
plan and rollout, so the exact wording in your workspace may differ.

Server URL:

```
https://mcp.currency-core.com/mcp
```

## Plan and workspace requirements

| Requirement | Detail |
|---|---|
| Plan | Custom MCP servers and full tool calls depend on your ChatGPT plan and workspace type. Feature availability has changed repeatedly, so check your workspace settings. |
| Admin permission | A workspace admin may need to allow custom connectors or MCP servers before members can add one. |
| Client | Use the web app. This page does not claim mobile support. |

If you do not see a custom server option, the cause is usually the plan or a
workspace policy, not the CurrencyCore URL. Check the current OpenAI
documentation for your workspace type rather than relying on a plan name.

## Setup

1. **Confirm you are in the right workspace.** Custom MCP servers are a workspace
   setting, not a personal preference.
2. **Open the workspace plugins or connectors area.** This is in workspace
   settings. On some plans it appears as a plugins directory with an option to add
   a custom MCP server.
3. **Choose the option to add a custom MCP server.**
4. **Enter a name and the server URL.** Use `CurrencyCore` for the name and
   `https://mcp.currency-core.com/mcp` for the URL.
5. **Connect the server.** ChatGPT starts the OAuth flow, which normally opens a
   browser for sign-in.
6. **Sign in to CurrencyCore and choose an organization.** The connection is
   bound to that organization.
7. **Start a new chat** and send a test prompt.

There is no JSON config file for this path. If a guide tells you to paste
`mcpServers` JSON into ChatGPT, it is describing a different client.

## Verify

Ask:

> Use the CurrencyCore convert tool to convert 500 USD to INR and include the
> rate date.

A working connection returns a conversion and a date. If ChatGPT answers from
memory, confirm the server is connected for that workspace and that the tool is
enabled in the chat.

## What a successful call returns

A successful tool call returns the REST body as text, a structured copy for
clients that support it, and metering metadata:

```json
{
  "content": [
    {
      "type": "text",
      "text": "{\"from\":\"USD\",\"amount\":500,\"date\":\"2026-11-10\",\"results\":[{\"to\":\"INR\",\"result\":41725.0,\"rate\":83.45}]}"
    }
  ],
  "structuredContent": {
    "from": "USD",
    "amount": 500,
    "date": "2026-11-10",
    "results": [{ "to": "INR", "result": 41725.0, "rate": 83.45 }]
  },
  "_meta": {
    "currencycore/tool_calls": 1,
    "currencycore/billed_requests": 1,
    "currencycore/status": 200
  }
}
```

Read `structuredContent` when your client supports it. Read `content[0].text`
when it does not. Check `_meta["currencycore/billed_requests"]` to confirm the
call counted against the organization; a public reference call or a failed call
returns `0`.

## Tool refresh behavior

ChatGPT freezes the tool list it discovered when the connector was added. If the
CurrencyCore server adds or changes tools, an existing chat may not see the
change.

- Start a new chat after a server change.
- Refresh or reconnect the connector if the option is available.
- If a tool you expect is missing, remove and re-add the connector, then start a
  new chat.

The 14 CurrencyCore tools and their plans are listed in
[MCP tools](/docs/mcp-tools/). Client-side caching can make a newly added tool
appear late.

## What ChatGPT can call

Core tools: `convert`, `get_rates`, `get_rates_by_base`, `get_history`,
`get_ppp_factor`, plus the public `list_countries` and `list_currencies`.

Analytics tools: `analyze_history`, `analyze_ppp`, `analyze_volatility`,
`analyze_correlation`, `analyze_drawdown`, `analyze_safe_haven`,
`analyze_mean_reversion`. These require Growth or higher.

Each successful keyed call counts as one API request against the organization's
monthly quota. MCP uses no AI credits.

## Gotchas

| Problem | Why it happens | Fix |
|---|---|---|
| No custom MCP option | The workspace type may not include it, or an admin has not allowed it | Ask an admin to enable custom connectors, or use Claude, Cursor, or VS Code. |
| The connector was added, but tools never run | The workspace connection is not authorized, or the chat has tools disabled | Reconnect and complete OAuth, then start a new chat. If only two tools appear and no browser opens, see the [troubleshooting note for older deployments](/docs/mcp-troubleshooting/#only-two-tools-and-no-sign-in-prompt). |
| The tool list is stale | ChatGPT caches the tools discovered at connect time | Refresh the connector or start a new chat. |
| The wrong organization is billed | The connection is bound to the organization chosen at consent | Remove and re-add the connector, then choose the correct organization. |
| `403` on analytics | The organization is on Free or Starter | Upgrade to Growth or higher, or use a core tool. |
| `429` on a busy workspace | The organization shares one monthly quota and rate limit across REST and MCP | Wait for the reset, or upgrade. |

## Related

- [MCP OAuth and access](/docs/mcp-oauth/)
- [MCP troubleshooting](/docs/mcp-troubleshooting/)
- [MCP for Claude](/docs/mcp-claude/)
- [MCP for VS Code](/docs/mcp-vscode/)
- [MCP for Cursor](/mcp-for-cursor/)