Anthropic · CCDV-F
Tool implementation
CCDV-F · Lesson 19 of 21 · 2:57:01
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In this lesson
Prepare for the Claude Certified Developer – Foundations exam, on the exam guide version 1.0, effective July 2026. In this lesson: the harness that dispatches tool calls and returns every result in one message, client tools versus server tools, detailed tool descriptions, errors with is_error, approval gates for side effects, small tool sets, and tool search. Includes three original practice questions.
Preview the topics
- Driftwood’s agent keeps calling search_orders when buyers ask about the status of a refund, which another tool returns, and the description of search_orders says only “Searches orders.” What should the team fix first?
- Driftwood’s shipping tool times out now and then, and the harness then returns an empty result, so Claude tells buyers that their parcel has no tracking data. What should the tool return instead?
- Driftwood’s agent has 120 tools from six services, their definitions fill a large part of every request, and Claude often picks a similar tool from the wrong service. Which change fits?