CCDV-F Agents and the Agent SDK Practice Question
A developer is building a Claude agent with the Anthropic SDK that must look up live order status. The agent has one tool named get_order_status, and its input_schema declares a required string property order_id. During testing, Claude returns a tool_use block with name "get_order_status" and input {"order_id": "A-4471"}. What must the developer's application do next to keep the agent loop running correctly?
⚠ Common exam trap
The trap here is assuming the model executes tools itself, when in fact the client application must run the tool and return a correlated tool_result block.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Execute the lookup, then send a user-role message containing a tool_result block with the matching tool_use_id back to Claude.
The agent loop alternates model reasoning with client-side tool execution. When Claude emits a tool_use block, the developer's code runs the named tool and returns the output as a tool_result content block in a user message, keyed by the same tool_use_id. That correlation lets Claude pair the result with its request and produce the final answer using real order data.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Call the tool, then send the raw JSON output as a plain assistant text message so Claude can read the order details directly.
Why it's wrong here
Results must be returned in a tool_result block associated with the originating tool_use_id, not as assistant-role prose. Injecting assistant text also forges the model's own turn, which the API rejects as an invalid sequence. Claude cannot reliably correlate free-form text with the pending get_order_status request, so the loop breaks.
- ✗
Append Claude's tool_use block to the conversation and immediately call the Messages API again with the same parameters to obtain the final answer.
Why it's wrong here
Simply re-invoking the API without supplying a tool_result leaves the model with an unanswered tool request; the loop never receives the order data. The tool_use block is the model's request, not its result. Claude needs the outcome of get_order_status before it can answer, so resubmitting the same request cannot produce a grounded final response.
- ✗
Convert the tool_use block into a system message so the model treats the tool request as persistent instructions for the rest of the session.
Why it's wrong here
System messages carry instructions and context; they are not the channel for tool execution results. Moving a tool_use block into the system role neither executes get_order_status nor satisfies the model's pending request, and it corrupts the expected message ordering. The tool result must be returned as a tool_result block tied to the tool_use_id.
- ✓
Execute the lookup, then send a user-role message containing a tool_result block with the matching tool_use_id back to Claude.
Why this is correct
This is the required half of the agent loop: the client executes the tool and returns its output to Claude as a tool_result content block inside a user-role message, with tool_use_id matching the originating tool_use block. Only then can Claude continue reasoning with the real data. This scenario's single tool call maps directly onto that pattern.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Anthropic exam blueprint
This CCDV-F practice question is part of Courseiva's free Anthropic certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CCDV-F exam.