What Is an MCP Connector? How to Add One to Claude, ChatGPT and Le Chat

01Introduction

An MCP connector is the link between your AI assistant and an outside tool. You add it once in your assistant's settings, and from then on the assistant can use that tool in any conversation.

The tool on the other end is an MCP server, a service built on the Model Context Protocol (MCP), the open standard AI assistants use to connect to outside tools. If you want the background on the protocol itself, read What Is MCP? The Model Context Protocol in Plain English. This guide is the practical part: what you need, where to click in Claude, ChatGPT and Le Chat, and what to ask once the connector is live.

The worked example throughout is ApyHub MCP, a single connector that gives your assistant access to the ApyHub catalog of over 1,500 API endpoints and capabilities, and growing. The steps are the same for any remote MCP server.

02Connector, server, plugin, app: the words

Each assistant uses its own name for the same idea, which makes searching for help confusing. Here is how the terms map.

A connector can bring in two kinds of things. Some connectors bring your data into the chat, such as your email, docs or project tracker. Others add capabilities, work the assistant can't do on its own, such as converting a file, checking a registry or fetching a live exchange rate. ApyHub is the second kind.

03What you need before you start

1. A connector URL. For a remote MCP server this is one HTTPS address. ApyHub runs two regions:
   • EU: https://mcp.eu.apyhub.com
   • US: https://mcp.us.apyhub.com
2. An account with the service. For ApyHub, the free tier needs no card and includes 5 API calls per day and up to 3,000 atoms per month. Atoms are ApyHub's usage unit: each call costs atoms according to the work it performs.
3. An assistant plan that allows connectors. Custom connectors are tied to specific plans and, on team workspaces, to admin permissions. The steps below note where this applies.

Pick the region that matches your ApyHub account. The official MCP Registry lists each region with its own key, so an EU key belongs with the EU URL and a US key with the US URL.

04How to add an MCP connector to Claude

In Claude, a server you add by URL is called a custom connector. According to Anthropic's help center, the steps for individual Pro and Max plans are:

1. Open Customize > Connectors.
2. Click +, then Add custom connector.
3. Paste the server URL, for example https://mcp.eu.apyhub.com.
4. Click Add.
5. Complete the sign-in. For ApyHub, a browser window opens and you log in to your ApyHub account.

On Team and Enterprise plans, an Owner adds the connector once under Organization settings > Connectors, then Add > Custom > Web. Each member then finds it under Customize > Connectors, marked with a "Custom" label, and clicks Connect.

To use it in a chat, click + at the bottom left of the message box, open Connectors, and switch the connector on for that conversation. You can turn individual connectors on and off per chat.

If a server authenticates with a fixed API key instead of a sign-in page, Claude's add-connector dialog has a Request headers section for it. ApyHub supports both: browser sign-in for everyday use, or an Authorization: Bearer <your API key> header for headless setups.

ApyHub has been approved for Claude's connector directory. Until the listing is published, add it as a custom connector using the steps above.

05How to add an MCP connector to ChatGPT

ChatGPT groups connectors under Plugins. ApyHub is listed in the ChatGPT Plugins directory as ApyHub EU, so there is no URL to paste:

1. Open Plugins in the ChatGPT sidebar.
2. Search for ApyHub EU and select Install plugin.
3. Sign in to ApyHub when ChatGPT asks.
4. In any chat, type @ApyHub EU followed by your request.

On Business and Enterprise workspaces, an admin may need to allow the plugin first. For the full walkthrough and a long list of prompts by category, see How to Extend ChatGPT's Capabilities With Plugins.

06How to add an MCP connector to Le Chat

Mistral's Le Chat supports custom MCP connectors. The Mistral documentation describes the flow:

1. Open the Connectors page from the Le Chat sidebar.
2. Click + Add Connector.
3. Switch to the Custom MCP Connector tab.
4. Fill in the fields:
   • Connector name: a unique identifier with no spaces, for example apyhub
   • Server URL: https://mcp.eu.apyhub.com
   • Description (optional): "API catalog for files, validation and live data"
5. Connect and complete the ApyHub sign-in.

On organization workspaces, Mistral requires an administrator to add connectors, so members may need to ask their admin.

The EU endpoint is a natural fit here. ApyHub B.V. is a Dutch company, and the EU region runs on EU infrastructure, which suits teams that chose Le Chat for data residency reasons.

07Developer tools: Claude Code, Cursor and VS Code

Developer tools use the same URL in a config file or command.

Claude Code takes one command:

claude mcp add --transport http apyhub https://mcp.eu.apyhub.com

Cursor reads remote servers from .cursor/mcp.json:

{
  "mcpServers": {
    "apyhub": {
      "url": "https://mcp.eu.apyhub.com"
    }
  }
}

VS Code reads them from .vscode/mcp.json:

{
  "servers": {
    "apyhub": {
      "type": "http",
      "url": "https://mcp.eu.apyhub.com"
    }
  }
}

The ApyHub MCP page has a copy-ready block for each client, including Claude Desktop, Codex CLI and ChatGPT. ApyHub states setup takes under 5 minutes.

08Where to find MCP connectors you can trust

You can add any server by URL, which is also the risk. A connector can read what you send it and act for you, so it's worth knowing who runs it. Three places to look:

• Your assistant's own directory. Claude's connector directory and ChatGPT's Plugins directory review listings before publishing them.
• The official MCP Registry at registry.modelcontextprotocol.io. Servers publish under a namespace tied to a domain the publisher controls. ApyHub is listed as com.apyhub/mcp-server-eu and com.apyhub/mcp-server-us.
• Community directories such as Glama, which list servers with setup details and status.

Before you connect anything, check four things:

1. Who publishes it. A named company with a domain you recognize, or an anonymous repository.
2. Where your data goes. Which region it runs in, how long it keeps what you send, and which other companies touch it.
3. What it can do. Reading data is low risk. Sending, paying and deleting deserve a closer look and an approval step.
4. How it signs you in. A sign-in flow or a scoped key you can revoke is better than a password shared into a chat.

ApyHub publishes these answers per service. Every API in the catalog carries machine-readable certification that records data handling, retention and alignment with GDPR, SOC 2 and ISO 27001, and every endpoint is available through ApyHub MCP, so your assistant can discover, evaluate and call it without a hand-written wrapper or tool definition. You can also choose which APIs your assistant can see. Anything you leave out stays invisible to the model.

Connect ApyHub MCP →

09Your first three workflows

Once the connector is on, describe the task in plain words. The assistant searches the catalog, picks the endpoint and runs it. These three work in Claude, ChatGPT and Le Chat.

1. Check a supplier before you pay them

This runs Validate EU VAT, VAT Company Lookup and Validate IBAN in one request.

2. Turn a PDF statement into a spreadsheet

This uses PDF to Excel. The file goes to the tool and only the result comes back to the chat, so a 40-page statement doesn't fill the conversation. ApyHub measures this at 75% fewer tokens on the same task for documents, images, video and audio.

3. A weekly rank report for a client

This runs the SERP Rank Checker once per keyword. Ask the same question next week and the assistant calls the same tool with the same rules, so the two reports compare cleanly.

For more workflows grouped by job, from invoice intake to CV screening, see the ApyHub MCP page.

10Common problems and fixes

• The connector doesn't show up in the chat. It's added but switched off for that conversation. In Claude, open + > Connectors and turn it on.
• Sign-in fails or returns "unauthorized". Check the region. An EU account needs the EU URL, and a US account needs the US URL.
• "Add custom connector" is missing. Your plan or workspace role doesn't allow custom connectors. On team plans, ask an Owner or admin to add it.
• The assistant answers from memory instead of using the tool. Name the task more concretely ("validate this VAT number against the EU registry") or ask it directly to use ApyHub.
• You hit a limit on the free tier. The daily cap of 5 calls usually comes first. Paid plans raise both the daily and monthly limits.

11Conclusion

An MCP connector is a saved link from your assistant to an MCP server. In Claude and Le Chat you add one as a custom connector by pasting the server URL. In ChatGPT you install it from the Plugins directory. Developer tools take the same URL in a command or config file.

Start with a connector from a publisher you can check, confirm where it runs and what it can do, and try it on a task you already do by hand. ApyHub gives you one connector for a catalog of APIs, with the data handling of each one documented before you call it.

Explore the catalog →

12Sources

• Anthropic Help Center, "Get started with custom connectors using remote MCP": support.claude.com
• Mistral documentation, "MCP Connectors" in Le Chat: docs.mistral.ai
• Official MCP Registry, ApyHub server entries: registry.modelcontextprotocol.io

13FAQ

What is an MCP connector? An MCP connector is the link between an AI assistant and an MCP server. Once it's added, the assistant can use that server's tools in your conversations.

What's the difference between an MCP connector and an MCP server? The server is the service that runs the tools. The connector is the saved connection to that server inside your assistant.

How do I add a custom connector to Claude? On Pro and Max, open Customize > Connectors, click +, choose Add custom connector, paste the server URL and click Add. On Team and Enterprise, an Owner adds it under Organization settings > Connectors first.

Can I add MCP connectors to ChatGPT? Yes. ChatGPT calls them plugins. ApyHub is listed as ApyHub EU in the Plugins directory, and you call it in a chat with @ApyHub EU.

Does Le Chat support MCP connectors? Yes. Open Connectors, click + Add Connector, choose the Custom MCP Connector tab, and enter a name and the server URL.

Which ApyHub URL should I use? Use https://mcp.eu.apyhub.com for an EU account and https://mcp.us.apyhub.com for a US account. The URL and the account need to be in the same region.

Are MCP connectors safe? A connector is as safe as the server behind it and the permissions you grant. Use servers from publishers you can identify, check where your data goes, and require approval for actions that send, pay or delete.

Can I use MCP connectors for workflow automation? Yes. One request can chain several tools, for example validating a VAT number, checking the IBAN and drafting a confirmation email. The assistant runs each call in order and passes the results along.

How can I test an ApyHub API before connecting it to my assistant? Every API page in the catalog has a "Try it" option in the browser. You can also use Voiden, a free, open-source API client that stores requests as Markdown files, or any HTTP client such as curl.

Is ApyHub MCP free? The free tier needs no card and includes 5 API calls per day and up to 3,000 atoms per month. Paid plans raise both limits.

14About ApyHub

ApyHub is a curated API catalog and trusted operational layer for developers and AI agents, with over 1,500 endpoints or capabilities and growing. Teams use the whole catalog through a single subscription priced in atoms, a unit that reflects the actual work each call performs. Every endpoint ships with machine-readable certification aligned with GDPR, SOC 2 and ISO 27001, and is MCP-ready by default, so AI agents can discover and call it through ApyHub MCP without custom wrappers. ApyHub is headquartered in Amsterdam, with offices in the Netherlands, Greece and India, and serves 65,000+ developer workspaces every month. The free tier requires no card. Building an API of your own? Become a provider →