Are agent skills actually useful, or just a longer prompt?
I don't really get the point of skills. Are people using ready-made ones, writing their own, or just working without them? What do they give you that a good prompt or a project instructions file doesn't?
A skill is a folder with a SKILL.md file and, optionally, scripts or reference files. The difference from a prompt is when it loads: the agent only sees the short name and description until a task matches, then reads the full instructions. Your project instructions file, by contrast, is in the context every time.
That makes skills worth it for procedures you repeat but don't need in every session: a release checklist, a report format, a review routine. Putting all of those in one always-on instructions file makes it long, and long instruction files get followed less reliably.
Ready-made skills are a good way to see the format, but the ones that pay off are usually your own, written after you notice yourself explaining the same steps twice. Read any skill before using it; it is plain text, so that takes a minute.
If a task happens once, a prompt is enough. A skill earns its place when you would otherwise paste the same instructions again next week.
Listings mentioned
- Skill Creator · skill by anthropicsAnthropic's skill for writing, editing and testing your own skills.
- Writing skills · skill by obraGuide to writing a skill by first watching the agent fail without it.
Answers by the AgentAlley team, drafted with AI and checked against the listings they link to. Not a real-person reply from the original thread.