How to add Locus MCP to ChatGPT (Developer mode)

Setup, step by step

1. Step 1

   Create a Locus Pro account

   Sign up at paywithlocus.com/pro. The Free plan has no subscription. Paid calls use prepaid credits.

2. Step 2

   Turn on Developer mode

   In ChatGPT, open Settings → Apps → Advanced settings and turn on Developer mode. OpenAI’s docs also list the toggle under Settings → Security and login. In a company workspace, an admin may need to allow it first.

3. Step 3

   Create the Locus app

   Open Plugins → Create app. Enter the MCP server URL and choose OAuth.

   MCP server URL: https://api.paywithlocus.com/api/credits/mcp
   Authentication: OAuth

4. Step 4

   Approve Locus

   ChatGPT opens Locus sign-in and consent. Approve it, then create the app. The grant includes offline_access so ChatGPT can refresh its short-lived token.

5. Step 5

   Select Locus Pro in a chat

   Start a Work task, open Plugins, and select Locus Pro before asking it to use a tool.

6. Step 6

   Check the connection

   Ask: What’s my Locus balance? A balance reply means the app, OAuth, and tools all work.

Which ChatGPT plans can use Locus?

OpenAI lists Developer mode for Plus, Pro, Business, Enterprise, and Edu accounts on the web. Full modify and write MCP requires an eligible Business, Enterprise, or Edu workspace.

Locus calls that spend credits are write actions. ChatGPT asks you to confirm write actions by default, so review the tool input before you approve it.

Can I upload the Locus skills to ChatGPT?

Not reliably yet. ChatGPT’s Skills picker may reject valid skill archives. If it does, keep the MCP app and have ChatGPT call the get_locus_guide tool. It returns the same versioned operating guides.

A rejected skill upload is not an MCP failure. The custom app still provides every Locus tool.

How do I fix a ChatGPT MCP OAuth error?

Delete the app and create it again with the exact URL above and OAuth selected. Then finish the Locus approval in the same browser.

• Check there is no trailing slash or extra path on the URL.
• Choose OAuth, not No Authentication.
• If the chat cannot see Locus tools, select Locus Pro from Plugins in that chat.
• Refresh the app from its settings page after Locus adds tools.

What can ChatGPT do with Locus connected?

ChatGPT can search the Locus catalog, read an endpoint schema and price, and run the call against your credit balance. You do not need an account or key with each provider.

Useful first asks: find a company website, verify a work email, or search the web with sources. Each paid call shows its charge in the result.