Using multiple tools

📖 Lesson content

Summary

Adding multiple tools to your Claude implementation becomes straightforward once you have the core tool-handling infrastructure in place. This tutorial shows how to integrate additional tools by following a simple pattern.

The Tools We're Adding

We need three main capabilities for our reminder system:

• Get current date time - Claude needs to know the current date and time
• Add duration to date time - Claude isn't perfect with date time addition
• Set a reminder - Need a way to set a reminder

The good news is that most of the implementation work is already done. The add_duration_to_datetime function and set_reminder function are provided, along with their corresponding schemas.

Adding Tools to the Conversation

First, update the run_conversation function to include the new tool schemas in the tools list:

response = chat(messages, tools=[
    get_current_datetime_schema,
    add_duration_to_datetime_schema,
    set_reminder_schema
])

This tells Claude about all three available tools it can use during the conversation.

Updating the Tool Router

Next, modify the run_tool function to handle the new tool calls. Add elif cases for each new tool:

def run_tool(tool_name, tool_input):
    if tool_name == "get_current_datetime":
        return get_current_datetime(**tool_input)
    elif tool_name == "add_duration_to_datetime":
        return add_duration_to_datetime(**tool_input)
    elif tool_name == "set_reminder":
        return set_reminder(**tool_input)

The pattern is simple: check the tool name, call the corresponding function with the provided input, and return the result.

Testing Multiple Tool Usage

To test the system, try a request that requires multiple tools: "Set a reminder for my doctors appointment. Its 177 days after Jan 1st, 2050."

This request forces Claude to:

1. Calculate the date (using add_duration_to_datetime)
2. Set the reminder (using set_reminder)

Claude handles this by first explaining what it needs to do, then making the appropriate tool calls in sequence. The conversation shows Claude calculating June 27, 2050 as the target date, then setting the reminder for that date.

Understanding the Message Flow

When you examine the conversation history, you'll see the complete message structure:

• User message with the request
• Assistant message containing both text and tool use blocks
• Tool result messages
• Follow-up assistant messages

This demonstrates how Claude can include multiple blocks in a single message - combining explanatory text with tool usage requests.

The Simple Pattern for Adding Tools

Once you have the core tool infrastructure, adding new tools follows this pattern:

1. Create the tool function implementation
2. Define the tool schema
3. Add the schema to the tools list in run_conversation
4. Add a case for the tool in run_tool

This modular approach makes it easy to expand your AI assistant's capabilities without restructuring existing code. Each new tool integrates seamlessly with the existing conversation flow and tool-handling logic.

Downloads

• 001_tools_009.ipynb

🔁 Related lessons

• Next: Fine grained tool calling
• Previous: Implementing multiple turns
• Same section: Making a request · Multi-Turn conversations · Chat exercise
• Part of paths: Path C
• Reference docs: Glossary · Skills atlas · By use-case

📚 Source & attribution

• Original Anthropic Academy lesson: https://anthropic.skilljar.com/claude-with-the-anthropic-api/287749
• © 2025 Anthropic. Educational fair-use only.