pocketflow/docs/design_pattern/agent.md

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---
layout: default
title: "Agent"
parent: "Design Pattern"
nav_order: 6
---
# Agent
Agent is a powerful design pattern, where node can take dynamic actions based on the context it receives.
To express an agent, create a Node (the agent) with [branching](../core_abstraction/flow.md) to other nodes (Actions).
> The core of build **performant** and **reliable** agents boils down to:
>
> 1. **Context Management:** Provide *clear, relevant context* so agents can understand the problem.E.g., Rather than dumping an entire chat history or entire files, use a [Workflow](./workflow.md) that filters out and includes only the most relevant information.
>
> 2. **Action Space:** Define *a well-structured, unambiguous, and easy-to-use* set of actions. For instance, avoid creating overlapping actions like `read_databases` and `read_csvs`. Instead, unify data sources (e.g., move CSVs into a database) and design a single action. The action can be parameterized (e.g., string for search) or programmable (e.g., SQL queries).
{: .best-practice }
### Example: Search Agent
This agent:
1. Decides whether to search or answer
2. If searches, loops back to decide if more search needed
3. Answers when enough context gathered
```python
class DecideAction(Node):
def prep(self, shared):
context = shared.get("context", "No previous search")
query = shared["query"]
return query, context
def exec(self, inputs):
query, context = inputs
prompt = f"""
Given input: {query}
Previous search results: {context}
Should I: 1) Search web for more info 2) Answer with current knowledge
Output in yaml:
```yaml
action: search/answer
reason: why this action
search_term: search phrase if action is search
```"""
resp = call_llm(prompt)
yaml_str = resp.split("```yaml")[1].split("```")[0].strip()
result = yaml.safe_load(yaml_str)
assert isinstance(result, dict)
assert "action" in result
assert "reason" in result
assert result["action"] in ["search", "answer"]
if result["action"] == "search":
assert "search_term" in result
return result
def post(self, shared, prep_res, exec_res):
if exec_res["action"] == "search":
shared["search_term"] = exec_res["search_term"]
return exec_res["action"]
class SearchWeb(Node):
def prep(self, shared):
return shared["search_term"]
def exec(self, search_term):
return search_web(search_term)
def post(self, shared, prep_res, exec_res):
prev_searches = shared.get("context", [])
shared["context"] = prev_searches + [
{"term": shared["search_term"], "result": exec_res}
]
return "decide"
class DirectAnswer(Node):
def prep(self, shared):
return shared["query"], shared.get("context", "")
def exec(self, inputs):
query, context = inputs
return call_llm(f"Context: {context}\nAnswer: {query}")
def post(self, shared, prep_res, exec_res):
print(f"Answer: {exec_res}")
shared["answer"] = exec_res
# Connect nodes
decide = DecideAction()
search = SearchWeb()
answer = DirectAnswer()
decide - "search" >> search
decide - "answer" >> answer
search - "decide" >> decide # Loop back
flow = Flow(start=decide)
flow.run({"query": "Who won the Nobel Prize in Physics 2024?"})
```