What message types do MCP clients and servers exchange?

Once an MCP client and server are connected, they exchange specific message types defined in the MCP specification. The two main ones you will work with are: a list tools request with its corresponding list tools result, where the client asks the server what tools do you provide and gets back a list of available tools. And a call tool request with its corresponding call tool result, where the client asks the server to run a specific tool with given arguments and then receives the results. There are similar request and result pairs for resources and prompts, but tools are the most common starting point when you first work with the protocol.