README example cannot run

[ndtoan96]

Describe the bug
The example under Tool cannot run.

To Reproduce
Steps to reproduce the behavior:

1. Create a project with below code

use rmcp::{tool, tool_router, ServiceExt, transport::stdio};

#[derive(Clone)]
struct Calculator;

#[tool_router(server_handler)]
impl Calculator {
    #[tool(description = "Add two numbers")]
    fn add(&self, #[tool(param)] a: i32, #[tool(param)] b: i32) -> String {
        (a + b).to_string()
    }
}

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    let service = Calculator.serve(stdio()).await?;
    service.waiting().await?;
    Ok(())
}

2. Try to run it
3. See the error

error: expected non-macro attribute, found attribute macro `tool`
 --> src\main.rs:9:21
  |
9 |     fn add(&self, #[tool(param)] a: i32, #[tool(param)] b: i32) -> String {
  |                     ^^^^ not a non-macro attribute

Expected behavior
It should run successfully.

Additional context

• Dependency: rmcp = { version = "1.5.0", features = ["server", "transport-io"] }
• rust version 1.95.0
• OS: Windows