MCP Servers vs ChatGPT Actions: Which Should You Use?

Two Ways to Give AI Tools

ChatGPT Actions (formerly plugins) and MCP servers both solve the same problem: giving AI models access to external tools and APIs. But they solve it very differently, with different trade-offs for developers and teams.

How ChatGPT Actions Work

ChatGPT Actions require an OpenAPI specification that describes your API endpoints. You upload this spec to OpenAI, configure authentication, and ChatGPT can call those endpoints during conversations.

The flow:

1. Write an OpenAPI spec (or generate one from your API)
2. Host the API with CORS headers for OpenAI
3. Configure auth (OAuth, API key, or none)
4. Register as a GPT Action in ChatGPT
5. ChatGPT calls your endpoints based on user questions

How MCP Servers Work

MCP servers expose typed tool definitions over a standard protocol (SSE or stdio). Any MCP-compatible client discovers available tools and calls them during conversations.

The flow:

1. Create an MCP server (manually or via DataFaucet in 60 seconds)
2. Server exposes tool definitions with typed parameters
3. Client connects, fetches tool list
4. Client calls tools as needed during conversations

The Key Differences

Client Lock-in

ChatGPT Actions: Only work inside ChatGPT. Build an Action and it only works for ChatGPT users. Want it in Claude? Build a separate integration. Cursor? Another one.

MCP Servers: Work with any MCP client. One server works simultaneously with ChatGPT, Claude, Cursor, Copilot, Windsurf, JetBrains, and every other MCP-compatible tool. Build once, use everywhere.

Setup Complexity

ChatGPT Actions: Require a valid OpenAPI spec. Most apps don't have one. Writing a spec from scratch takes hours. The spec must be hosted at a publicly accessible URL. Auth configuration has specific requirements (callback URLs, scopes).

MCP Servers: Can be created without any spec. DataFaucet captures API calls from normal browsing and generates the server automatically. No OpenAPI spec needed. No public URL hosting for your API.

Protocol Standard

ChatGPT Actions: Proprietary to OpenAI. No cross-client compatibility. OpenAI can change requirements, deprecate features, or modify behavior without notice (they deprecated plugins and replaced with Actions already).

MCP Servers: Open protocol (Model Context Protocol). Maintained by Anthropic but used across the industry. Multiple implementations, growing ecosystem, standard transport (SSE/stdio).

Discoverability

ChatGPT Actions: Tools are embedded in a GPT. Users must find and enable the specific GPT to access tools.

MCP Servers: Tools are discovered automatically when a client connects. No user action beyond adding the server URL to config.

Real-time Data

ChatGPT Actions: Call your API in real-time during conversations. Data is as fresh as your API.

MCP Servers: Same. Call tool endpoints in real-time. No difference here.

Comparison Table

When to Use ChatGPT Actions

• You already have a public API with an OpenAPI spec
• Your users are exclusively on ChatGPT
• You want to distribute tools through the GPT Store
• You need OAuth-based per-user authentication through OpenAI

When to Use MCP Servers

• You need tools that work across multiple AI clients
• The target app has no OpenAPI spec (most don't)
• You want hosted infrastructure without managing your own API server
• You need tools deployed in seconds, not hours
• You want an open standard that won't be deprecated

Can You Use Both?

Yes. ChatGPT now supports MCP servers in addition to Actions. You can:

1. Create an MCP server with DataFaucet
2. Connect it to ChatGPT via MCP settings
3. Same server also works with Claude, Cursor, and everything else

This gives you the best of both: ChatGPT users get tool access, and so does everyone else.

The Industry Direction

The trend is clear: every major AI client is adopting MCP. ChatGPT, Claude, Cursor, Copilot, Windsurf, JetBrains, Google ADK. Actions are legacy. MCP is the standard.

Building on MCP means your tools work today and continue working as new clients launch. Building on Actions means rebuilding every time a new client gains market share.