---
title: "Adding a custom MCP server to Claude and ChatGPT"
source: "Simon Willison 博客（Atom）"
source_tier: "t2"
url: "https://simonwillison.net/2026/Jul/29/mcp-in-claude-and-chatgpt/#atom-everything"
permalink: "https://feed.astralor.com/items/itm_088e271325ae4fa3c9452971"
published: "2026-07-29T00:13:18.000Z"
score: 76
channel: "tech"
tags: ["Anthropic","ChatGPT","Claude","MCP","OpenAI","Custom Integration"]
---

# Adding a custom MCP server to Claude and ChatGPT

## AI commentary

> This article is a must-read for every developer interested in AI extensibility. MCP is becoming the 'standard socket' for tool chains, and Willison shows in the most intuitive way how to plug in your own 'tool plug'. It is especially useful for users building workflows with Claude/ChatGPT—the methods here can be directly reused.

## At a glance

Simon Willison shares a detailed guide on how to add custom MCP servers to the web chat UIs of Claude and ChatGPT. The Model Context Protocol (MCP) enables AI assistants to access external tools and data sources, but setup is not obvious. The author demonstrates the configuration process through hands-on examples and discusses the protocol's potential to extend AI capabilities.

## Key points

- MCP allows AI models to call external tools, databases, and APIs, breaking free from the model's built-in knowledge. 
- Both Claude's and ChatGPT's web chat UIs support MCP, but adding a custom server requires manual configuration.
- The author provides a complete tutorial from writing a server to enabling it in the chat interface.
- MCP enables developers to enhance AI assistants like adding plugins, greatly improving their practicality.

## Full text

I've started exploring [MCP](https://modelcontextprotocol.io/) in more detail. The web chat UIs for both Claude and ChatGPT can access MCP servers but it's not obvious how to set them up. Here's …

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