Awesome! This is a strong improvement, and your revised flow matches the right direction 
First, excellent work iterating this quickly.
Removing the empty transfer node
Good change.
That node was structurally redundant and could accidentally re-propagate state in unsafe ways.
Your new flow is cleaner and has fewer places for state merge errors.
Switching to ToolNode()
Also a very good change.
Using ToolNode reduces manual wiring mistakes around tool call execution and ToolMessage formatting/pairing etc.
One decision node + parallel tool execution
Your reasoning is correct.
Multiple decision (LLM) nodes usually add extra model hops (latency/cost), while the main speed-up comes from parallelizing tool execution after one decision step.
Your revised flowchart reflects this correctly.
Making “current time” a tool
This is valid, especially if “current time” is not always needed.
One nuance:
- if time is needed for every request, inject it once in context/state (cheaper)
- if time is conditional, exposing it as a tool is a good pattern
You are doing exactly what strong engineers do: build, observe failures, simplify architecture, and iterate with evidence. Good job @Huimin-station 