strands_agents.py

"""
Strands Agent with Web Search - Harvard Holiday Schedule Example

Uses the Strands Agents SDK to create an AI agent backed by Claude on AWS Bedrock
(via Harvard's Apigee gateway) with a local web_search tool powered by DDGS.

The agent searches the web for Harvard's current holiday schedule and writes
the results to a markdown file.

Install
-------
    pip install strands-agents ddgs

Optional tools package (not required here, provides pre-built tools like
file_read, shell, use_browser, retrieve, etc.):
    pip install strands-agents-tools

Environment variables
---------------------
    APIGEE_API_KEY  Harvard Apigee API key for the Bedrock gateway

Usage
-----
    python strand_agents.py
"""
from strands import Agent, tool
from strands.models.bedrock import BedrockModel
from ddgs import DDGS
from datetime import date
import os

# function to add custom headers to the request
def add_custom_headers(request, **kwargs):
    request.headers.add_header('api-key', os.environ[f'APIGEE_API_KEY'])

bedrock_model = BedrockModel(
    model_id="us.anthropic.claude-opus-4-6-v1",
    region_name="us-east-1",
    endpoint_url=f"https://go.apis.huit.harvard.edu/ais-bedrock-llm/v2",
)
# Register custom Apigee header on the client BedrockModel created internally
bedrock_model.client.meta.events.register_first('before-sign.bedrock-runtime.*', add_custom_headers)

@tool
def web_search(query: str) -> str:
    """Search the web for current information using DuckDuckGo (no API key required).

    Args:
        query: The search query string.

    Returns:
        A string containing the top search results with titles, URLs, and snippets.

    Available backends (pass via backend param): brave, duckduckgo, google, grokipedia,
        mojeek, wikipedia, yahoo, yandex. Defaults to "auto" (rotates engines).
    """
    results = list(DDGS().text(query, max_results=5, backend="google"))
    return "\n\n".join(
        f"[{r['title']}]({r['href']})\n{r['body']}"
        for r in results
    )

# 2. Initialize the agent, providing the model and the web_search tool
agent = Agent(
    model=bedrock_model,
    tools=[web_search],
    system_prompt=f"You are a Human Resources specialist for Harvard University. Today's date is {date.today()}."
)

# 3. Invoke the agent with a prompt that requires searching the web
response = agent("""Provide information about the university's holiday schedule and identify the next upcoming holiday for staff members. 
                 Use the web_search tool to find the most current information on Harvard's official website or other reliable sources.
                 What is the next upcoming holiday for staff members? List holidays with dates and whether they have already passed 
                 or are upcoming.""")
# 4. Write the response to a markdown file
with open("harvard_holiday_schedule.md", "w") as f:
    f.write(str(response))