[Python] Langgraph tools_condition prebuilt method routing to other nodes instead of END node

I was building quite a simple graph using Langgraph. I decided the pre-built tools_condition function from langgraph. So I imported it and used it as follows:

graph_builder = StateGraph(State)
graph_builder.add_node("chatbot", assistant)
graph_builder.add_node("tools", lambda state: run_tool(state, tools={"athena_query":athena_query}))
graph_builder.add_node("report_checker", report_check)

graph_builder.add_edge(START, "chatbot")
graph_builder.add_conditional_edges(
"chatbot",
tools_condition
)
# graph_builder.add_edge("chatbot", "tools")
graph_builder.add_edge("tools", "chatbot")
graph_builder.add_edge("chatbot", "report_checker")

graph = graph_builder.compile(checkpointer=memory)


The resulting graph is the following:



It does not make sense that there is a conditional edge pointing from assistant to report_checker when I specify that it is a regular edge. Why is the default behaviour of tools_condition to make conditional edges to everything else if its not a tool call and not just go to END?

I know this because if I pass the routing arguments of where it is supposed to go, the extra conditional edges disappear:

graph_builder = StateGraph(State)
graph_builder.add_node("chatbot", assistant)
graph_builder.add_node("tools", lambda state: run_tool(state, tools={"athena_query":athena_query}))
graph_builder.add_node("report_checker", report_check)

graph_builder.add_edge(START, "chatbot")
graph_builder.add_conditional_edges(
"chatbot",
tools_condition,
{
"END": END,
"tools": "tools",
}
)
graph_builder.add_edge("tools", "chatbot")
graph_builder.add_edge("chatbot", "report_checker")

graph = graph_builder.compile(checkpointer=memory)


The unwanted conditional edge is now gone:



Why is default tools_condition routing the main node somewhere other than the END node?

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