How to Create a Simple Agent¶

Problem: You want to create a basic agent that responds to user messages.

Time: 5 minutes

Prerequisites: - AgentFlow installed - LLM API key configured

Quick Solution¶

from agentflow.graph import StateGraph, END, Agent
from agentflow.state import AgentState, Message

# Create agent
agent = Agent(
    model="google/gemini-2.5-flash",
    system_prompt="You are a helpful assistant."
)

# Build workflow
workflow = StateGraph(state_schema=AgentState)
workflow.add_node("agent", agent)
workflow.set_entry_point("agent")
workflow.add_edge("agent", END)

# Compile and run
app = workflow.compile()
result = app.invoke({"messages": [Message.text_message("Hello!", "user")]})
print(result["messages"][-1].content)

Step-by-Step¶

1. Import Required Modules¶

from agentflow.graph import StateGraph, END, Agent
from agentflow.state import AgentState, Message

2. Create the Agent¶

agent = Agent(
    model="google/gemini-2.5-flash",  # Choose your LLM
    system_prompt="You are a helpful assistant."  # Agent instructions
)

Model options: - "openai/gpt-4o" - OpenAI GPT-4 - "google/gemini-2.5-flash" - Google Gemini - "anthropic/claude-3-5-sonnet-20241022" - Anthropic Claude

3. Build the Workflow¶

workflow = StateGraph(state_schema=AgentState)
workflow.add_node("agent", agent)
workflow.set_entry_point("agent")
workflow.add_edge("agent", END)

4. Compile¶

app = workflow.compile()

5. Send Messages¶

result = app.invoke({
    "messages": [Message.text_message("Your question here", "user")]
})

# Get response
response = result["messages"][-1].content
print(response)

Verification¶

Run your script. You should see a response from the agent:

$ python my_agent.py
Hello! How can I help you today?

Common Options¶

Set Custom System Prompt¶

agent = Agent(
    model="google/gemini-2.5-flash",
    system_prompt="You are an expert Python developer. Give concise code examples."
)

Use Environment Variable for API Key¶

import os
from dotenv import load_dotenv

load_dotenv()  # Loads .env file

agent = Agent(model="openai/gpt-4o", system_prompt="...")
# API key loaded automatically from OPENAI_API_KEY env variable

Troubleshooting¶

"No API key provided"¶

Set your API key in environment:

export OPENAI_API_KEY=sk-...
# or
export GOOGLE_API_KEY=...
# or
export ANTHROPIC_API_KEY=...

"Invalid model name"¶

Use correct format: "provider/model-name" - ✅ "openai/gpt-4o" - ❌ "gpt-4o"

Next: Customize System Prompts →