Hi @syd ,
Thank you so much, that helped. 
Found a similar solution in this post as well: Deep Agents: Custom state fields not accessible in ToolRuntime.state - OSS Product Help / LangGraph - LangChain Forum.
In addition, if you want to access a variable across multiple agents and tools, you can also store it in runtime.store and later retrieve it. This can slightly reduce the latency and complexity in my opinion.