​
📘 Overview

This intermediate tutorial demonstrates how to:
  • Define multiple agent types (class-based, decorator-based)
  • Use tools for data retrieval
  • Use custom_start to override agent logic
  • Orchestrate them in a flow using TaskFlow
In this flow, a user input goes through three stages:
  1. ResearchAgent fetches content
  2. SummarizerAgent condenses it
  3. ReporterAgent formats the result as a final report

​
📦 File Structure

research_flow.py

​
🔧 Step 1 — Define a Tool

from chainless import Tool

def mock_web_search(query: str) -> str:
    return f"[MOCK] Web search results for: '{query}'"

web_tool = Tool(
    name="WebSearch",
    description="Searches the web for information on a given topic.",
    func=mock_web_search
)

​
🧠 Step 2 — ResearchAgent (Custom Start)

This agent uses the web tool and formats the tool result into a paragraph. 
from chainless import Agent
from langchain_deepseek import ChatDeepSeek

llm = ChatDeepSeek(model="deepseek-chat")

research_agent = Agent(
    name="ResearchAgent",
    llm=llm,
    tools=[web_tool],
    system_prompt="You're a research assistant. Use the WebSearch tool if needed."
)

@research_agent.custom_start
def run_research(input: str, tools, llm, system_prompt):
    tool_result = tools[0].execute({"query": input})
    prompt = f"{system_prompt}nnTopic: {input}nnTool Output: {tool_result}nnWrite a research paragraph."
    return llm.invoke(prompt)

​
🧾 Step 3 — SummarizerAgent (Standard)

summarizer_agent = Agent(
    name="SummarizerAgent",
    llm=llm,
    system_prompt="Summarize the given research in a concise paragraph."
)

​
📤 Step 4 — ReporterAgent (AgentProtocol)

This agent implements AgentProtocol and formats output as an email. 
class ReporterAgent:
    name = "ReporterAgent"

    def start(self, input: str, **kwargs):
        return {
            "output": f"Subject: Weekly Research ReportnnDear Reader,nn{input}nnBest regards,nYour AI Assistant"
        }

​
🔗 Step 5 — TaskFlow Assembly

from chainless import TaskFlow

flow = TaskFlow(name="ResearchReportFlow")

# Add agents
flow.add_agent("research", research_agent)
flow.add_agent("summarize", summarizer_agent)
flow.add_agent("report", ReporterAgent())

# Define steps
flow.step("research", {"input": "{{input}}"})
flow.step("summarize", {"input": "{{research.output}}"})
flow.step("report", {"input": "{{summarize.output}}"})

# Run
result = flow.run("The impact of AI in modern education")
print(result["output"])

​
✅ Output Sample

Subject: AI Weekly

Dear Reader,

[Summarized research content here...]

Yours,
ChainlessBot

​
📌 Notes

  • add_agent(name, agent) registers agents
  • step(name, {inputs}) sets how data flows
  • Use {{previous.output}} syntax for chaining outputs
  • Agents can be class-based or decorator-based

​
🧪 Full Code: research_flow.py

research_flow.py
from chainless import Tool, Agent, TaskFlow
from langchain_deepseek import ChatDeepSeek

# Tool
def mock_web_search(query: str) -> str:
    return f"[MOCK] Web search results for: '{query}'"

web_tool = Tool(
    name="WebSearch",
    description="Searches the web for information on a given topic.",
    func=mock_web_search
)

# LLM
llm = ChatDeepSeek(model="deepseek-chat")

# Research Agent
research_agent = Agent(
    name="ResearchAgent",
    llm=llm,
    tools=[web_tool],
    system_prompt="You're a research assistant. Use the WebSearch tool if needed."
)

@research_agent.custom_start
def run_research(input: str, tools, llm, system_prompt):
    tool_result = tools[0].execute({"query": input})
    prompt = f"{system_prompt}nnTopic: {input}nnTool Output: {tool_result}nnWrite a research paragraph."
    return llm.invoke(prompt)

# Summarizer Agent
summarizer_agent = Agent(
    name="SummarizerAgent",
    llm=llm,
    system_prompt="Summarize the given research in a concise paragraph."
)

# Reporter Agent using AgentProtocol
class ReporterAgent:
    name = "ReporterAgent"

    def start(self, input: str, **kwargs):
        return {
            "output": f"Subject: Weekly Research ReportnnDear Reader,nn{input}nnBest regards,nYour AI Assistant"
        }

# Flow
flow = TaskFlow(name="ResearchReportFlow")

# Add agents
flow.add_agent("research", research_agent)
flow.add_agent("summarize", summarizer_agent)
flow.add_agent("report", ReporterAgent())

# Define steps
flow.step("research", {"input": "{{input}}"})
flow.step("summarize", {"input": "{{research.output}}"})
flow.step("report", {"input": "{{summarize.output}}"})

# Run
result = flow.run("The impact of AI in modern education")
print(result["output"])

​
✅ Output Example

[ResearchAgent] → Research paragraph...
[SummarizerAgent] → Concise summary...
[ReporterAgent] → Formatted email report...

​
🧠 Takeaways

  • Use Tool for modular utility
  • Combine Agent types (class, decorator) for flexibility
  • Extend with custom logic via custom_start
  • Chain steps clearly with TaskFlow

​
📌 Next

  • Add error handling, retries
  • Split tasks conditionally
  • Add memory/state passing between agents