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How to add an MCP server to Claude, Claude Code and ChatGPT

Exact steps to add a remote MCP server to Claude, Claude Code and ChatGPT, how to check it works, and what to do when sign-in loops. Desloppy is the worked example.

By the Desloppy team ·

To add an MCP server to Claude, open Settings, then Connectors, and pick Add custom connector. Paste the server's URL, click Connect, and sign in when the server asks. In Claude Code, run one command in your terminal: claude mcp add, with the server's name and URL. In ChatGPT, turn on Developer mode in the connector settings and create a connector with the same URL.

That is the short answer. Below are the exact steps for each app, with our own server as the example. Desloppy is an MCP server that checks writing for AI slop, and its address is https://desloppy.com/mcp. Swap in the URL of any other remote server and the steps stay the same.

What an MCP server is

MCP stands for Model Context Protocol. It is an open standard that lets an AI assistant use outside tools. The server offers the tools. The assistant (Claude, ChatGPT and others) decides when to call them. A remote server lives on the web, so there is nothing to install. You give the app a URL and sign in.

Desloppy offers six tools. check_writing gives a draft a Slop score and marks the lines that sound like default chatbot writing. quick_fixes runs instant rule checks and is free. ai_score gives the score alone. check_file does the same check on a Word, PowerPoint, PDF, text or Markdown file. learn_voice learns your writing style from text you say is yours. compare scores a before and an after side by side.

Add an MCP server to Claude

This works on claude.ai, the desktop app and the phone app.

  1. Open Settings and go to Connectors. On some versions the same page sits under Customize.
  2. Pick Add custom connector.
  3. Name it. For our server, type Desloppy.
  4. Paste the URL: https://desloppy.com/mcp
  5. Click Connect. A sign-in page opens. For Desloppy you sign in with your email or a passkey.
  6. You land back in Claude, connected.

One step people miss: a connector is not always on in every chat. If Claude does not use it, open the tools menu in the chat box and switch the connector on for that chat. Anthropic's help page on custom connectors has the current menu names.

Add an MCP server to Claude Code

Claude Code adds servers from the terminal. Most remote servers want a key in a header. For Desloppy, make a key on your account page first. The key is shown once, so copy it then. Then run:

claude mcp add --transport http desloppy https://desloppy.com/mcp --header "Authorization: Bearer YOUR_KEY"

Put your key where it says YOUR_KEY. To check it worked, run claude mcp list in the terminal, or type /mcp inside Claude Code. The server should show as connected.

Add an MCP server to ChatGPT

ChatGPT runs custom MCP servers through Developer mode.

  1. Open Settings, then Apps and Connectors, then Advanced, and turn on Developer mode.
  2. Create a new connector and paste https://desloppy.com/mcp as the URL.
  3. Sign in when the server's page opens.

If an app cannot do the sign-in step, most servers also take a key. For Desloppy, send the header Authorization: Bearer YOUR_KEY. Never put a key in the URL. URLs end up in logs, so Desloppy turns those requests away.

Check that it works

Ask in plain words. With Desloppy connected, try one of these:

  • "Deslop this."
  • "What's the Slop score on this email? Show me which lines and why."
  • "Check the speaker notes in this deck." (attach the file)

The assistant calls the tool, and a card shows the score and the marked lines. Desloppy only marks lines and says what to change. The words you keep are yours. To see what the score means, read What the Slop score is.

When something goes wrong

  • Sign-in keeps looping: remove the connector, add it again, and sign in with the same email as before.
  • The tool never runs: switch the connector on for that chat, or ask for it by name.
  • "Pick a plan to keep going": your free words ran out. Quick fixes still work without words.
  • The URL works for you but not for the app: Claude and ChatGPT reach remote servers from their own cloud, so the server must be on the public internet. A server behind a company network will not answer them.

What it costs

Adding a server costs nothing. Each server sets its own price. Desloppy gives 5,000 free words, one time, after you sign in, and the same words work on the website, in Claude and in ChatGPT. Paid plans start at $9 a month for 100,000 words. The text you check is never stored. Full setup notes are on the Desloppy MCP page, and you can try 1,000 words with no account at desloppy.com.