$ printf <3 JSON-RPC lines> | java -jar target/mcp-sdk-plain.jar stdio
{"jsonrpc":"2.0","id":1,"result":{"protocolVersion":"2025-06-18","capabilities":{"logging":{},"resources":{"subscribe":false,"listChanged":true},"tools":{"listChanged":true}},"serverInfo":{"name":"notes-server","version":"1.0.0"},"instructions":"Tools: word_stats, divide, explode. Resources: notes://readme and notes://{name}."}}
{"jsonrpc":"2.0","id":2,"result":{"content":[{"type":"text","text":"words=3 chars=13 longest=three"}],"isError":false}}