1  """
  2  Agent with Tools Example.
  3  This demonstrates how to create an AI agent that can use tools to accomplish tasks.
  4  """
  5  
  6  from langchain_community.llms import Ollama
  7  from langchain.agents import Tool, AgentExecutor, create_react_agent
  8  from langchain.prompts import PromptTemplate
  9  import math
 10  
 11  # Initialize Ollama
 12  llm = Ollama(
 13      model="gpt-oss:120b",
 14      base_url="http://192.222.50.154:11434",
 15      temperature=0  # More deterministic for tool use
 16  )
 17  
 18  # Define custom tools
 19  def calculator(expression: str) -> str:
 20      """
 21      A calculator tool that evaluates mathematical expressions.
 22      """
 23      try:
 24          # Safe evaluation of math expressions
 25          result = eval(expression, {"__builtins__": {}}, {
 26              "sin": math.sin,
 27              "cos": math.cos,
 28              "tan": math.tan,
 29              "sqrt": math.sqrt,
 30              "pi": math.pi,
 31              "e": math.e,
 32              "pow": pow,
 33              "abs": abs,
 34          })
 35          return str(result)
 36      except Exception as e:
 37          return f"Error: {str(e)}"
 38  
 39  def string_length(text: str) -> str:
 40      """
 41      Returns the length of a string.
 42      """
 43      return str(len(text))
 44  
 45  def reverse_string(text: str) -> str:
 46      """
 47      Reverses a string.
 48      """
 49      return text[::-1]
 50  
 51  # Create tool objects
 52  tools = [
 53      Tool(
 54          name="Calculator",
 55          func=calculator,
 56          description="Useful for mathematical calculations. Input should be a valid Python expression like '2 + 2' or 'sqrt(16)'. Available functions: sin, cos, tan, sqrt, pi, e, pow, abs."
 57      ),
 58      Tool(
 59          name="StringLength",
 60          func=string_length,
 61          description="Returns the length of a string. Input should be the string."
 62      ),
 63      Tool(
 64          name="ReverseString",
 65          func=reverse_string,
 66          description="Reverses a string. Input should be the string to reverse."
 67      )
 68  ]
 69  
 70  # Create ReAct prompt template
 71  template = """Answer the following questions as best you can. You have access to the following tools:
 72  
 73  {tools}
 74  
 75  Use the following format:
 76  
 77  Question: the input question you must answer
 78  Thought: you should always think about what to do
 79  Action: the action to take, should be one of [{tool_names}]
 80  Action Input: the input to the action
 81  Observation: the result of the action
 82  ... (this Thought/Action/Action Input/Observation can repeat N times)
 83  Thought: I now know the final answer
 84  Final Answer: the final answer to the original input question
 85  
 86  Begin!
 87  
 88  Question: {input}
 89  Thought: {agent_scratchpad}
 90  """
 91  
 92  prompt = PromptTemplate.from_template(template)
 93  
 94  # Create agent
 95  agent = create_react_agent(llm, tools, prompt)
 96  
 97  # Create agent executor
 98  agent_executor = AgentExecutor(
 99      agent=agent,
100      tools=tools,
101      verbose=True,
102      handle_parsing_errors=True,
103      max_iterations=5
104  )
105  
106  if __name__ == "__main__":
107      # Example queries that require tool use
108      queries = [
109          "What is the square root of 144 plus 10?",
110          "How long is the string 'LangChain is awesome!'?",
111          "Reverse the string 'Hello World' and tell me its length",
112          "Calculate 2 to the power of 8, then divide by 4"
113      ]
114  
115      for query in queries:
116          print("\n" + "=" * 60)
117          print(f"Query: {query}")
118          print("=" * 60)
119          try:
120              response = agent_executor.invoke({"input": query})
121              print(f"\nFinal Answer: {response['output']}\n")
122          except Exception as e:
123              print(f"Error: {str(e)}\n")