You are building a multi-agent research system using the Claude Agent SDK.

Option B introduces an evaluator-and-refinement loop at the correct orchestration layer. The coordinator already owns the research plan and delegation decisions, so it should inspect the synthesis result against the required questions, identify coverage gaps, and issue focused follow-up assignments. Anthropic’s description of its multi-agent research system follows this pattern: the lead agent synthesizes returned findings, determines whether additional research is required, and creates new subagents or refines its strategy before producing the final result. Increasing the initial query breadth, option A, may generate additional irrelevant material and cannot guarantee that unforeseen gaps will be covered. Option C merely documents the incompleteness instead of correcting it. Option D weakens role separation by giving the synthesis agent search capabilities, increasing tool complexity and bypassing the coordinator’s centralized tracking. Targeted re-delegation preserves specialized responsibilities and creates an observable sequence of research, evaluation, refinement, and resynthesis. The coordinator should also maintain explicit coverage criteria and limit the number of refinement rounds so the system improves completeness without entering an uncontrolled research loop.

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