What happens behind the scenes when you ask Claude a question via MCP?

Once the client functions are implemented, you can run your main application and ask something like what is the contents of the report PDF document. Behind the scenes, your application uses the client to fetch the available tools, then sends those tools and your question to Claude. Claude decides to use the read document contents tool. Your application uses the client to execute that tool against the MCP server. The server returns the document contents. Your application passes the result back to Claude, and Claude responds to you with an answer that incorporates the document data. The client is the bridge that makes all of this possible.