Update src/mcp.rs

src/mcp.rs

@@ -65,7 +65,9 @@ impl McpServer {
                 let init_result = json!({
                     "protocolVersion": "2024-11-05",
                     "capabilities": {
-                        "tools": {}
+                        "tools": {
+                            "listChanged": true
+                        }
                     },
                     "serverInfo": {
                         "name": "rust-mcp-search",
@@ -348,17 +350,39 @@ async fn handle_sse(
 ) -> (HeaderMap, Sse<impl Stream<Item = Result<Event, Infallible>>>) {
     let mut headers = HeaderMap::new();
     headers.insert("x-accel-buffering", HeaderValue::from_static("no"));
-    headers.insert(header::CACHE_CONTROL, HeaderValue::from_static("no-cache"));
+    headers.insert(header::CACHE_CONTROL, HeaderValue::from_static("no-cache, no-transform"));
     headers.insert(header::CONNECTION, HeaderValue::from_static("keep-alive"));
+    headers.insert(header::CONTENT_TYPE, HeaderValue::from_static("text/event-stream"));
 
-    let initial = tokio_stream::iter(vec![
+    // Emit initial endpoint AND tool availability notification immediately
+    let initial_events = vec![
         Ok(Event::default().event("endpoint").data("/rpc")),
-    ]);
+        Ok(Event::default().event("message").data(
+            json!({
+                "jsonrpc": "2.0",
+                "method": "notifications/tools/list_changed",
+                "params": {}
+            })
+            .to_string(),
+        )),
+    ];
+
+    let initial = tokio_stream::iter(initial_events);
 
-    let interval = tokio_stream::wrappers::IntervalStream::new(tokio::time::interval(Duration::from_secs(15)))
-        .map(|_| Ok(Event::default().comment("keep-alive")));
+    // 5-second heartbeats keep connection alive on Hugging Face Spaces proxy
+    let interval = tokio_stream::wrappers::IntervalStream::new(tokio::time::interval(
+        Duration::from_secs(5),
+    ))
+    .map(|_| Ok(Event::default().comment("keep-alive")));
 
     let stream = initial.chain(interval);
 
-    (headers, Sse::new(stream).keep_alive(KeepAlive::default()))
+    (
+        headers,
+        Sse::new(stream).keep_alive(
+            KeepAlive::new()
+                .interval(Duration::from_secs(5))
+                .text("keep-alive"),
+        ),
+    )
 }