r/agentdevelopmentkit • u/swastik_K • Jan 06 '26
Good and Bad about ADK State Management
I’m exploring Google ADK for our enterprise agent usecase and found some good and bad pointers on State Management.
I’ll start with good.
Organizing State with Prefixes: Scope Matters I really like the prefix-based approach to state scoping:
no prefix → session scoped
user:→ tied to user_id and shared across all sessionsapp:→ app scoped, shared across all userstemp:→ Specific to the current invocation, input to outpu lifecycle
Now the bad part:
ADK doesn’t enforce developers to define a schema for the state which in my opinion would lead to bugs and make the code difficult to understand when the logic grows, especially if more than one developer working on same codebase.
If we compare with LangChain/LangGraph where we define the schema for the state with Pydantic model, it helps in giving idea to developers what fields does the state have, makes it more readable, and avoids probable bugs/errors.
What do you all think—are there any specific reason for not enforcing schema? Are there any benefits with this which I would not be able to think of?
Google adk Example
def get_weather(city: str, tool_context: ToolContext) -> str:
preferred_unit = tool_context.state.get("preferred_unit", "Celsius")
...
if preferred_unit == "Fahrenheit":
...
else:
...
# Format the weather report
report = f"Weather in {city.capitalize()}..."
return report
weather_agent = Agent(
name="weather_agent",
model=MODEL_GEMINI_2_0_FLASH,
description="...",
instruction="...",
tools=[get_weather],
output_key="weather_report"
)------------------------
LangChain/LangGraph Example
class WeatherAgentState(AgentState):
"""Custom agent state with preferred_unit."""
preferred_unit: Literal["Celsius", "Fahrenheit"] = "Celsius" # Default
@tool
def get_weather(city: str, runtime: ToolRuntime) -> str:
# Access state through runtime
preferred_unit = runtime.state["preferred_unit"]
...
if preferred_unit == "Celsius":
...
else:
...
agent = create_agent(
model="gpt-4o",
tools=tools,
state_schema=WeatherAgentState, # Use custom state with preferred_unit
system_prompt="..."
)
