The CLAUDE.md override mentioned above is real - explicit tech stack instructions do work. Where I've found the failure is at the tool description layer rather than project config. Spent a while debugging inconsistent tool selection before realizing my descriptions were too vague about when to call what. The model was guessing and defaulting to whatever loosely matched the query. Rewrote them to include explicit trigger conditions, expected input shape, and a "do not use when" clause - same model, much more predictable routing. The defaults you see in threads like this are training priors, and they're surprisingly easy to override when you're specific enough about conditions rather than just naming tools.