How to use MCP servers with custom GPTs

Custom GPTs can gain access to external MCP-compatible tools by using an HTTP gateway that translates between Custom GPTs’ static, endpoint-based REST Actions and MCP servers’ dynamic JSON-RPC tool interface, which relies on the tools/list and tools/call methods. The gateway exposes each MCP capability as a separate REST endpoint, converts requests into MCP invocations, and returns responses in HTTP format, while an OpenAPI schema enables ChatGPT to recognize the available actions. Setup involves creating a Custom GPT, selecting authentication appropriate to the deployment stage, importing or generating an OpenAPI specification, and sharing the GPT with team members when applicable. For production use, the guidance recommends OAuth 2.0 for individual attribution and access control, secure credential storage, key rotation where needed, comprehensive logging, rate limits, audit trails, and reusable tool configurations. Open-source options such as mcpo can generate MCP-to-OpenAPI proxies, while managed gateways such as MintMCP can automate schema generation, authentication, SSO, user management, and auditing.

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