Handling message blocks

Making Requests with Tools

• Include a tools keyword argument when calling client. messages. create()
• The tools argument is a list containing JSON schema specifications for available tools
• This tells Claude which tools it can use to respond to user queries

Multi-Block Messages

• When Claude uses a tool, the response message contains multiple content blocks, not just text
• A tool-use response typically includes:
• Text block: explanatory text for the user about what Claude is doing
• Tool use block: specifies which tool Claude wants to call and what arguments to pass

Tool Use Block Structure

• Contains the name of the tool function Claude wants to call
• Includes the input arguments/parameters needed for that function
• Signals to developers that a tool execution is required

Managing Conversation History with Tools

• Claude does not store conversation history automatically
• Developers must manually maintain the full conversation history
• When appending assistant messages to the message list, include the entire content field (all blocks)
• This ensures Claude receives complete context when making follow-up requests

Updating Helper Functions

• Existing helper functions like add_user_message() and add_assistant_message() need updates
• They must support messages with multiple content blocks, not just single text blocks
• This allows proper handling of tool-use responses in the conversation flow

Takeaways

• Claude can use tools when you include a tools argument with JSON schema specifications in client. messages. create()
• Tool-use responses contain multiple content blocks: text explaining the action plus a tool-use block specifying which tool to call and its arguments
• Developers must manually maintain full conversation history, including all content blocks from assistant messages, so Claude has complete context for follow-up requests
• Helper functions need updates to handle multi-block messages instead of just single text blocks