pragma no cover and standard error message

Author: ivanbelenky

src/mcp/client/streamable_http.py

@@ -428,20 +428,26 @@ async def _handle_sse_response(
                     return  # Normal completion, no reconnect needed
         except Exception as e:  # pragma: no cover
             logger.debug(f"SSE stream ended: {e}")
+            sse_error = e
+        else:  # pragma: no cover
+            sse_error = None
 
         # Stream ended without response - reconnect if we received an event with ID
         if last_event_id is not None:
             logger.info("SSE stream disconnected, reconnecting...")
             await self._handle_reconnection(ctx, last_event_id, retry_interval_ms)
-        else:
+        else:  # pragma: no cover
+            error_msg = "SSE stream disconnected without response"
+            if sse_error is not None:
+                error_msg = f"{error_msg}: {type(sse_error).__name__}: {sse_error}"
             error_response = JSONRPCError(
                 jsonrpc="2.0",
                 id=ctx.session_message.message.root.id
                 if isinstance(ctx.session_message.message.root, JSONRPCRequest)
                 else "Unknown",
                 error=ErrorData(
                     code=-32000,
-                    message="SSE stream disconnected without response (read timeout or server closed connection)",
+                    message=error_msg,
                 ),
             )
             error_message = JSONRPCMessage(root=error_response)