MCP server or ChatGPT app: what should a dealer software vendor build?
ChatGPT apps, Claude connectors and Google's connected apps all run on MCP. Build one good MCP server and you can reach all of them. Here's how they relate and what to build first.
Every AI platform now has its own way to plug in a tool: ChatGPT apps, Claude connectors, Google's connected apps for Gemini and Search, Microsoft's agent tools. For a dealer software vendor deciding what to build, the good news is that they share a foundation.
They all run on MCP
- ChatGPT apps are built with OpenAI's Apps SDK, which uses MCP for the tools and adds optional interface components that render inside the chat.
- Claude connects to remote MCP servers as custom connectors, on the web, on desktop and in Claude Code.
- Google opened a preview in October 2026 that lets developers submit a cloud-hosted MCP server for Gemini and Search.
- A dealer's own agents, built on any framework, can call the same server.
So the choice isn't "ChatGPT app or MCP server." Build the MCP server; the app is a layer on top.
What to build first
- An MCP server over the API you already have. Start with reads for one area, such as inventory search or service appointment times. Days of work, not quarters. How to build an MCP agents actually understand covers tool naming and descriptions.
- Real sign-in. OAuth per user, scoped to what that user can see in your product. No shared admin keys.
- Honest annotations. Mark every tool read-only or as one that changes data or contacts a customer. Platforms increasingly reject servers that don't.
- Then the platform extras. A ChatGPT interface, directory submissions to ChatGPT, Claude and Google, each with its own review.
Test it before you submit it
- Run the free MCP Inspector (
npx @modelcontextprotocol/inspector) and call each tool by hand. - Plug it into the AutomotiveMCP test kit to see it work next to other dealer tools behind one gateway, with a live view of every call.
- Get it listed in the directory so dealers checking "does this vendor support MCP" find a yes. Then post your setup notes in your vendor thread on the forum.
Common questions
- Is a ChatGPT app the same as an MCP server?
- A ChatGPT app is built on an MCP server. OpenAI's Apps SDK uses MCP for the tools, and adds optional interface components that render inside ChatGPT. The same MCP server can also be added to Claude and other assistants.
- Should a dealer software vendor build a ChatGPT app or an MCP server first?
- The MCP server. It's the part every assistant can use: ChatGPT, Claude, Gemini, Copilot and a dealer's own agents. Once it works, add the ChatGPT-specific interface or submit it to each assistant's directory.
- What makes an MCP server get approved by ChatGPT or Google?
- Clear tool descriptions and honest annotations. Mark each tool as read-only or as one that changes data, keep scopes small, and require sign-in for anything that touches a dealer's or customer's data.