Equipping financial agents with curated procedural skill packages increases mean task performance from 0.366 to 0.528, whereas allowing agents to dynamically write and reuse their own skills yields negligible improvement while driving up compute costs. For production systems in high-stakes domains, this means you must invest engineering hours into building deterministic, pre-authored tool libraries and procedural guardrails rather than relying on expensive runtime self-generation. This shift drastically reduces error rates in complex quantitative workflows like portfolio construction and risk management while keeping API overhead low.