Developer productivity tools (S4)

Your developer productivity agent runs Grep to locate a symbol, then issues a Read call. The API returns stop_reason 'tool_use' after the Read response is sent. What does this tell the loop?

1. AThe model encountered an error during Read and the loop should retry the Read call.
2. BThe model wants to execute another tool; the loop must process the tool_use block and continue.
3. CThe loop should terminate because Read has finished and no more tools are needed.
4. Dstop_reason 'tool_use' is only returned after Bash calls; a Read result should show 'end_turn'.