//! Trivial connectivity-check tool.
//!
//! Flow: read the optional `message` argument → echo it back prefixed
//! with `"pong: "`, defaulting to `"pong"` when no message is supplied.
//!
//! Why: gives callers a cheap, dependency-free way to verify the tool
//! harness is reachable and responding before running real work.

use serde_json::{json, Value};
use anyhow::Result;
use super::super::Tool;
use super::super::ToolCtx;

/// Tool that echoes back a message; used for connectivity/latency checks.
pub struct Pong;

impl Tool for Pong {
    fn name(&self) -> &'static str {
        "pong"
    }

    fn description(&self) -> &'static str {
        "Simple connectivity check. Echoes back any input for health checks and latency testing."
    }

    fn parameters(&self) -> Value {
        json!({
            "type": "object",
            "properties": {
                "message": {
                    "type": "string",
                    "description": "Message to echo back"
                }
            }
        })
    }

    fn run(&self, _ctx: &ToolCtx, args: &Value) -> Result<String> {
        let msg = args.get("message")
            .and_then(|v| v.as_str())
            .unwrap_or("pong");
        Ok(format!("pong: {msg}"))
    }
}