MCP server

An MCP server is the program that sits between an AI assistant and one system, such as an ad account, a store or an email platform. It publishes a list of tools with their input schemas, answers tool calls by talking to the underlying API, and returns the result in a form the assistant can read. Some servers also publish resources (data to read) and prompts (reusable instructions).

Servers come in two shapes. A remote server is hosted by the vendor and reached over HTTPS, usually after an OAuth sign-in; you add it by URL. A local server runs on your own machine or infrastructure, often started with a command, and holds its credentials locally. The directory shows which shape each server takes under 'Hosting'.

The server decides what is possible, not the assistant. A read-only reporting server cannot change a campaign no matter how the prompt is phrased. A server with write tools can, which is why the access level and the vendor's own cautions matter more than the server's feature list when you pick one.