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ChatGPT Custom GPT with VMCP

This guide walks you through creating a Custom GPT with Actions that connects to your Virtual MCP (VMCP) servers through MintMCP.

Prerequisites​

Before starting, ensure you have:

  • A ChatGPT Plus, Pro, Team, or Enterprise account
  • A MintMCP account with at least one configured VMCP

Step 1: Get Your VMCP API Details​

  1. Navigate to your VMCP in the MintMCP dashboard
  2. Click on the VMCP you want to connect
  3. Navigate to the "Custom GPT" tab
  4. Choose your authentication method:
    • API Key Method: Best for personal use or when all activity can be attributed to your account
    • OAuth Method: Best for sharing with teammates when you need proper user attribution
VMCP Custom GPT details with authentication options

Step 2: Create a Custom GPT​

  1. Go to ChatGPT GPT Editor
  2. In the GPT Builder, configure:
    • Name: Give your GPT a descriptive name (e.g., "Google Workspace Assistant")
    • Description: Explain what this GPT does
    • Instructions: Add instructions for using VMCP tools

Step 3: Configure Actions​

  1. In the GPT Builder, navigate to "Configure"
  2. Click "Create new action"

Option A: API Key Authentication​

If you chose API Key method in Step 1:

  1. Paste the OpenAPI schema from MintMCP
  2. Configure Authentication:
    • Authentication Type: API Key
    • Auth Type: Bearer
    • API Key: Paste the API key from Step 1
Custom GPT API Key configuration

Option B: OAuth Authentication​

If you chose OAuth method in Step 1:

  1. Paste the OpenAPI schema from MintMCP
  2. Configure Authentication:
    • Authentication Type: OAuth
    • Client ID: Copy from MintMCP
    • Client Secret: Copy from MintMCP
    • Authorization URL: Copy from MintMCP
    • Token URL: Copy from MintMCP
    • Scope: offline_access
    • Token Exchange Method: Basic Authorization Header
Custom GPT OAuth configuration
  1. After saving, copy the "Callback URL" from ChatGPT
  2. Return to MintMCP Custom GPT tab and paste the Callback URL
  3. Click "Submit" to complete OAuth setup

Step 4: Test and Publish​

  1. Use the "Preview" panel to test your GPT
  2. Try a test query: 
    What emails have I received today?
  3. Verify the response matches your expectations
  4. Once tested, click "Create" and choose how you want to share the Custom GPT.

    For Team/Enterprise accounts​

    • Invite Only: Restricted to invited team members
    • Organization: Workspace sharing - require link or open to all members
    • Public: External sharing - via link or GPT Store

    For Plus/Pro accounts​

    • Only me: Private use only
    • Anyone with a link: Selective sharing
    • Public: GPT Store publication (if eligible)

Step 5: Using Your Custom GPT​

  1. Access your GPT from "My GPTs" or via shared link
  2. Start a conversation
  3. The GPT will automatically use VMCP tools when appropriate
  4. Authentication happens automatically based on your chosen method:
    • API Key: All actions use your account
    • OAuth: Each user authenticates with their own account

Choosing Between API Key and OAuth​

Use API Key when:​

  • Creating a personal Custom GPT
  • You're okay with all activity being attributed to your account
  • Simpler setup is preferred

Use OAuth when:​

  • Sharing the Custom GPT with teammates
  • You need proper user attribution for audit trails
  • Each user should use their own VMCP permissions