Exposing a MCP Server to OpenAI

Unlock MCP in ChatGPT with Inspectr

Since the summer of 2025, you can enable “Custom Connectors” in Developer Mode in ChatGPT to use remote MCP Servers!

With the MCP (Model Context Protocol), you can connect proprietary systems and apps to OpenAI, allowing you to search, reason, and act with any local MCP server in ChatGPT, right alongside web results and built-in connectors.

Inspectr makes it simple to expose your MCP server securely and inspect how ChatGPT uses your MCP tools, prompts, and resources.

What You’ll Learn

Enable Developer Mode in ChatGPT
Expose your local MCP server using Inspectr
Connect it to ChatGPT as a “custom connector”
Use your MCP server directly in ChatGPT conversations
Inspect requests and responses in the Inspectr UI

Prerequisites

A running MCP-compatible server (more info in the OpenAI MCP docs)
Inspectr installed (Install Guide →)

Step 1: Start Your MCP Server

Make sure your MCP server is running locally, using the “streamable http” as transport. For this example we run it on port 3000.

mcp-server --port 3000

Step 2: Expose MCP via Inspectr

Run Inspectr with the --expose flag:

inspectr \
  --listen=:8080 \
  --backend=http://localhost:3000 \
  --expose \
  --channel=mcp-demo \
  --channel-code=mcpserver123

Your MCP server is now available at:

https://mcp-demo.in-spectr.dev/mcp

Inspectr listens on port 8080
Forwards traffic to your MCP server on port 3000
Captures and displays traffic in the App UI at http://localhost:4004

Step 3: Enable Developer Mode in ChatGPT

Go to “Settings” → “Connectors” → “Advanced settings”

and enable Developer Mode.

Step 4: Add a Custom Connector

In ChatGPT, go to “Settings” → “Connectors”

After enabling Developer Mode, click “Create” to add a new connector.

Fill in the connector details, for example:

Name: Inspectr
Description: Inspectr MCP Server
MCP Server URL: https://mcp-demo.in-spectr.dev/mcp
Authentication: “No authentication” (or set to the method your MCP server requires)
Tick “I trust this application”

Press “Create” to save the connector. ChatGPT will then attempt to connect to your MCP server.

Once connected, you should see connection details and a list of available actions.

Step 5: Use Inspectr in ChatGPT

Once connected, you can select the connector, and the MCP server will appear under “Use tools” in the composer.

You can now run prompts that leverage the tools inside the MCP server and see the results directly in the chat.

For example, let’s run a prompt that searches for the most used API endpoints:

Next we want see how the response times behaves:

View MCP Requests in Inspectr

To view how ChatGPT interacts with your MCP server; including tools, prompts, and resources — go to http://localhost:4004, where you’ll find a history of requests and responses.

Requests made by ChatGPT

Responses from the MCP server

Summary

Inspectr makes it easy to:

Expose your local MCP server to OpenAI ChatGPT
Monitor and review how ChatGPT uses your MCP tools, prompts, and resources