Late reply, but the answer is: 1) there is a fair amount of behind the scenes work going on that I dont want the agent to have access too or know about. Tools make it very easy to have strong control over what can and cannot be done. File system access is built directly into the tool, which makes it much easier to be confident about what it has access too, since the thing that actually has the permissions is the tools code, not the agent. 2) Portability, I can host it from a single spot and serve it to multiple models on different machines easily, which is very desirable for me. 3) I can update the configuration of the tool independent of a skill.

A skill wouldn't be a bad option though, and I highly recommend creating one yourself! The ability to customize our workflows and tools to a high degree is one of the largest strengths of agentic coding.