A developer productivity agent has a web_search tool and an MCP code_search tool. Both have clear, distinct descriptions. The system prompt includes: "When the user asks you to search, use web_search to find the answer." Requests like "search the repo for callers of parseConfig" keep going to web_search. What is the most effective fix?

Answer: B — Reword the system prompt instruction so "search" is no longer tied to web_search

The descriptions are already clear. A keyword-sensitive instruction in the system prompt links the word 'search' to web_search and overrides them. Rewording or removing that instruction fixes the cause (b). More description detail (a) can't outweigh a prompt that points the other way. Few-shot examples (c) add tokens to work around an instruction you control. Removing web_search (d) breaks legitimate web lookups.