There’s nothing super special about it, it’s just handy if you have some instructions that you don’t need the AI to see all the time, but that you’d like it to have available for specific things.

Maybe you have a custom auth backend that needs an annoying local proxy setup before it can be tested—you don’t need all of those instructions in the primary agents.md bloating the context on every request, a skill would let you separate them so they’re only accessed when needed.

Or if you have a complex testing setup and a multi-step process for generating realistic fixtures and mocks: the AI maybe only needs some basic instructions on how to run the tests 90% of the time, but when it’s time to make significant changes it needs info about your whole workflow and philosophy.

I have a django project with some hardcoded constants that I source from various third party sites, which need to be updated periodically. Originally that meant sitting down and visiting a few websites and copy pasting identifiers from them. As AI got better web search I was able to put together a prompt that did pretty well at compiling them. With a skill I can have the AI find the updated info, update the code itself, and provide it some little test scripts to validate it did everything right.

you could for example create a skill to access your database for testing purposes and pass in your tables specifications so that the agent can easily retrieve data for you on the fly.

There can be a Django template skill for example, which is just a markdown file which reminds the LLM the syntax of Django Templates and best practices for it. It could have an included script that the LLM can use to test a single template file for example.

Skills are not useful for single-shot cases. They are for: cross-team standardization (for LLM generated code), and reliable reusability of existing code/learnings.

Skills are the matrix scene where neo learns kungfu. Imagine they are a database of specialized knowledge that can an agent can instantly tap into _on demand_.

The key here is “on demand”. Not every agent or convention needs to know kung fu. But when they do, a skill is waiting to be consumed. This basic idea is “progressive disclosure” and it composes nicely to keep context windows focused. Eg i have a metabase skill to query analytics. Within that I conditionally refer to how to generate authentication if they arent authenticated. If they are authenticated, that information need not be consumed.

Some practical “skills”: writing tests, fetching sentry info, using playwright (a lot of local mcps are just flat out replaced by skills), submitting a PR according to team conventions (eg run lint, review code for X, title matches format, etc)