Stdio transport

In the stdio transport:

1. The client launches the MCP server as a subprocess.
2. The server reads JSON-RPC messages from its standard input (stdin) and sends messages to its standard output (stdout).
3. Messages are individual JSON-RPC requests, notifications, or responses.
4. Messages are delimited by newlines, and MUST NOT contain embedded newlines.
5. The server MAY write UTF-8 strings to its standard error (stderr) for logging purposes. Clients MAY capture, forward, or ignore this logging.
6. The server MUST NOT write anything to its stdout that is not a valid MCP message.
7. The client MUST NOT write anything to the server’s stdin that is not a valid MCP message.

sequenceDiagram
    participant Client
    participant Server Process

    Client->>+Server Process: Launch subprocess
    loop Message Exchange
        Client->>Server Process: Write to stdin
        Server Process->>Client: Write to stdout
        Server Process--)Client: Optional logs on stderr
    end
    Client->>Server Process: Close stdin, terminate subprocess
    deactivate Server Process