Step-by-step SKILL.md packages an AI follows for a single kind of task.
A skill is a focused playbook - instructions, examples and constraints - that makes any model reliable at one job, from SQL reporting to changelog writing. The router fills a plan's skill slot with the best match for the request.
When the user wants to understand or optimize for SERP feature types (PAA, sitelinks, rich results, AI Overviews). Also use when the user mentions "SERP," "SERP features," "search result features," "P