Microsoft’s open-source SkillOpt framework automatically improves “agent skills” stored as text files, such as Markdown (.md) instruction documents, without retraining the underlying language model. The approach treats the skill document itself as the optimizable object and keeps the target model’s weights frozen. SkillOpt runs an iterative propose-and-test loop: it executes a batch of tasks using an initial skill, collects execution trajectories as feedback, and an offline optimizer analyzes successes versus failures to propose structural edits (add, delete, or replace) to the skill text. Proposed edits are filtered for contradictions or duplicates, ranked by expected utility, and applied under an “edit budget” that limits how far the document can change in each step. Each candidate skill is then evaluated on a separate held-out validation set; improvements are accepted, while non-improving edits are rejected and stored to provide negative feedback so the optimizer does not repeat the same changes. Sources report that SkillOpt adds deep-learning-inspired controls—learning-rate-like edit budgeting, validation gating, and an epoch-level “momentum” update—intended to reduce skill drift and regressions. Reported results include improved accuracy across multiple models, benchmarks, and execution harnesses, with claims of strong portability across model scales and environments. Usage requires representative, scorable feedback and an evaluation harness for verification.