langchain_tools.py

from langchain_core.prompts import ChatPromptTemplate
from langchain_anthropic import ChatAnthropic  # or langchain_openai.ChatOpenAI
from langchain_core.tools import tool
from langchain_core.pydantic_v1 import BaseModel

# Define a tool using the @tool decorator
@tool
def multiply(x: int, y: int) -> int:
    """Multiply two integers."""
    return x * y

# Define output schema
class OutputSchema(BaseModel):
    result: int

# Create prompt template
prompt = ChatPromptTemplate.from_messages([
    ("system", "You can use tools to help answer questions."),
    ("user", "{input}")
])

# Initialize LLM and bind tools
llm = ChatAnthropic(api_key="YOUR_KEY", model="claude-3-5-sonnet-20240620")
llm_with_tools = llm.bind_tools([multiply])

# Enable structured output
structured_llm = llm_with_tools.with_structured_output(OutputSchema, include_raw=True)

# Compose the chain
chain = prompt | structured_llm

# Run the chain
result = chain.invoke({"input": "What is 6 times 7?"})
print(result["parsed"])