Macro mcp_error

macro_rules! mcp_error {
    (parse $msg:expr) => { ... };
    (invalid_request $msg:expr) => { ... };
    (method_not_found $method:expr) => { ... };
    (invalid_params $msg:expr) => { ... };
    (internal $msg:expr) => { ... };
    (unauthorized $msg:expr) => { ... };
    (forbidden $msg:expr) => { ... };
    (not_found $resource:expr) => { ... };
    (tool_not_found $tool:expr) => { ... };
    (validation $msg:expr) => { ... };
    (rate_limit $msg:expr) => { ... };
}

Macro for quick error creation