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ChatGPT Developer Mode: Full Access to MCP Connectors

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Great news, everyone! OpenAI has finally launched Developer Mode for ChatGPT — full Model Context Protocol (MCP) support with all read and write tools. This is exactly what we've all been waiting for!

What is ChatGPT Developer Mode?

It's a beta feature that unlocks full MCP client access. Now ChatGPT can work with any MCP connectors — both for reading data and modifying it. Sounds awesome, but there's a catch: the mode is quite powerful and potentially dangerous, so it's designed for developers who understand what they're doing.

Who Can Access It and How to Enable?

Requirements:

  • ChatGPT Pro or Plus subscription
  • Access via web version

How to activate:

  1. Go to ChatGPT settings
  2. Select Settings → Connectors → Advanced → Developer mode
  3. Enable developer mode

Setting Up MCP Connectors

Once developer mode is activated, you can add remote MCP servers:

  • Supported protocols: SSE and streaming HTTP
  • Authentication: OAuth or no authentication
  • Tool management: you can enable/disable individual tools in connector settings

Using in Conversations

Here's where it gets interesting! A "Developer Mode" option appears in the composer for selecting connectors. But there are nuances with prompting:

Best Prompting Practices:

Be maximally specific:

Use the "Acme CRM" connector's "update_record" tool to...

Disallow alternatives:

Do not use built-in browsing or other tools; 
only use the Acme CRM connector.

Specify sequencing:

First call Repo.read_file with { path: "..." }. 
Then call Repo.write_file with the modified content. 
Do not call other tools.

Examples of Effective Prompts:

Schedule a 30-minute meeting tomorrow at 3pm PT with 
alice@example.com and bob@example.com using "Calendar.create_event".
Do not use any other scheduling tools.

Create a pull request using "GitHub.open_pull_request" from branch 
"feat-retry" into "main" with title "Add retry logic". 
Do not push directly to main.

Write Action Confirmation

This is important! By default, all write actions require confirmation. ChatGPT will show the JSON payload before execution — carefully review what exactly will be sent. Incorrect write actions can inadvertently destroy or corrupt data!

You can set up automatic confirmation for trusted tools during a conversation, but be cautious.

Why Do We Need This?

Developer Mode opens incredible possibilities for automation and integration. Now ChatGPT can:

  • Read and modify files in repositories
  • Manage CRMs and databases
  • Create calendar events
  • Integrate with any APIs through MCP

What About FastMcp?

By the way, we already have ready-to-use connectors for ChatGPT on FastMcp! No need to set up MCP servers yourself — just take and use them. We're constantly adding new connectors for popular services.

Visit our website, choose the connectors you need, and connect them to your ChatGPT in just a few clicks. Save time on setup and focus on solving problems!

Takeaways

Developer Mode in ChatGPT is a serious step forward for the MCP ecosystem. Finally, we have full protocol support in one of the most popular AI assistants.

Sure, it's still a beta version with limitations, but the potential is enormous. Combined with ready-made connectors from FastMcp, it becomes a powerful tool for workflow automation.

Try it out, experiment, and share your experience in the comments!