As a software engineer
I want to create a private scratchpad MCP tool as private_scratchpad_tool.rs
So that private scratchpads to be created, updated and retrieved

Given public_scratchpad_tool.rs exists and reflects public_scratchpad_controller.rs
And public_scratchpad_tool.rs and private_scratchpad_controller.rs call scratchpad_service.rs
When private_scratchpad_tool.rs is created
Then it should reflect public_scratchpad_tool.rs and private_scratchpad_controller.rs
And include all controller endpoints as MCP tools with #[tool] annotations

Provide unit tests where applicable to private_scratchpad_tool.rs.