Every subagent in a multi-agent research system was given the same 18 tools. Tool selection errors are frequent, and the synthesis agent runs its own web searches in about a third of tasks. What is the most effective change?

Answer: D — Give each subagent only the tools its role needs, removing web search from synthesis

Too many tools degrade selection, and agents tend to misuse tools outside their specialization. Scoping each subagent to the four or five tools its role needs fixes both (d). A prompt prohibition (a) leaves the tool available and the long list in place. Merging into generic tools (b) makes descriptions vaguer and contracts weaker. tool_choice 'any' (c) forces a tool call. It doesn't make selection better or remove the search tool.