The Last 20% Agents reliably deliver the first 80% of a solution — the ingestion, the endpoints, the schema, the pipeline — and quietly skip the 20% that makes it something a person would love. Asked for an enterprise knowledge wiki, an agent builds the crawler, the embeddings, the LLM synthesis layer, and never once asks what a wiki page should read like , which pages should exist, or how someone finds an answer on day one. The result compiles, passes tests, demos fine, and is dead on arrival. This skill exists to find that 20%, spec it as concretely as the plumbing, and finish it. Why the 2…