MCP upgrade: API client method signature backward compatibility
When upgrading MCP server API clients (e.g., aiohttp→httpx), never remove “unused” parameters from method signatures without grepping all callers first. Tool modules call API client methods with positional/keyword args inherited from the old interface. Removing an unused param like get_trending(category) — where the API ignores category — breaks callers that pass it. The on_duplicate="error" flag catches duplicate tool names at startup but won’t catch method signature mismatches — those fail silently until runtime. Always: grep -rn "api_client.<method>" src/tools/ before changing any method signature.