gh-hiroshi75-protografico-protografico/skills/langgraph-master/02_graph_architecture_workflow_vs_agent.md

Workflow vs Agent

Differences and usage between Workflow and Agent.

Basic Differences

Workflow

"predetermined code paths and are designed to operate in a certain order" (Predetermined code paths, operates in specific order)

• Pre-defined: Processing flow is clear
• Predictable: Follows same path for same input
• Controlled Execution: Developer has complete control over control flow

Agent

"dynamic and define their own processes and tool usage" (Dynamic, defines its own processes and tool usage)

• Dynamic: LLM decides next action
• Autonomous: Self-determines tool selection
• Uncertain: May follow different paths with same input

Implementation Comparison

Workflow Example: Translation Pipeline

def translate_node(state: State):
    return {"text": translate(state["text"])}

def summarize_node(state: State):
    return {"summary": summarize(state["text"])}

def validate_node(state: State):
    return {"valid": check_quality(state["summary"])}

# Fixed flow
builder.add_edge(START, "translate")
builder.add_edge("translate", "summarize")
builder.add_edge("summarize", "validate")
builder.add_edge("validate", END)

Agent Example: Problem-Solving Agent

def agent_node(state: State):
    # LLM determines tool usage
    response = llm_with_tools.invoke(state["messages"])
    return {"messages": [response]}

def should_continue(state: State):
    last_message = state["messages"][-1]
    # Continue if there are tool calls
    if last_message.tool_calls:
        return "continue"
    return "end"

# LLM decides dynamically
builder.add_conditional_edges(
    "agent",
    should_continue,
    {"continue": "tools", "end": END}
)

Selection Criteria

Choose Workflow When

✅ Structure is Clear

• Processing steps are known in advance
• Execution order is fixed

✅ Predictability is Important

• Compliance requirements exist
• Debugging needs to be easy

✅ Cost Efficiency

• Want to minimize LLM calls
• Want to reduce token consumption

Examples: Data processing pipelines, approval workflows, translation chains

Choose Agent When

✅ Problem is Uncertain

• Don't know which tools are needed
• Variable number of steps

✅ Flexibility is Needed

• Different approaches based on situation
• Diverse user questions

✅ Autonomy is Valuable

• Want to leverage LLM's judgment
• ReAct (reasoning + action) pattern is suitable

Examples: Customer support, research assistant, complex problem solving

Hybrid Approach

Many practical systems combine both:

# Embed Agent within Workflow
builder.add_edge(START, "input_validation")  # Workflow
builder.add_edge("input_validation", "agent")  # Agent part
builder.add_conditional_edges("agent", should_continue, {...})
builder.add_edge("tools", "agent")
builder.add_conditional_edges("agent", ..., {"end": "output_formatting"})
builder.add_edge("output_formatting", END)  # Workflow

ReAct Pattern (Agent Foundation)

Agent follows the ReAct (Reasoning + Acting) pattern:

1. Reasoning: Think "What should I do next?"
2. Acting: Take action using tools
3. Observing: Observe results
4. Repeat until reaching final answer

# ReAct loop implementation
def agent(state):
    # Reasoning: Determine next action
    response = llm_with_tools.invoke(state["messages"])
    return {"messages": [response]}

def tools(state):
    # Acting: Execute tools
    results = execute_tools(state["messages"][-1].tool_calls)
    return {"messages": results}

# Observing & Repeat
builder.add_conditional_edges("agent", should_continue, ...)

Summary

Aspect	Workflow	Agent
Control	Developer has complete control	LLM decides dynamically
Predictability	High	Low
Flexibility	Low	High
Cost	Low	High
Use Case	Structured tasks	Uncertain tasks

Important: Both can be built with the same tools (State, Node, Edge) in LangGraph. Pattern choice depends on problem nature.

Related Pages

• 02_graph_architecture_prompt_chaining.md - Workflow pattern example
• 02_graph_architecture_agent.md - Agent pattern details
• 02_graph_architecture_routing.md - Hybrid approach example