Comment by verdverm

I use "harness" for the tool which calls the llm, has the tools, interacts with the computer (filesys, bash, etc), does the session bookeeping

and "agent" as the instance which is running... this is the more overloaded term because there are "agent" definitions, this is where a combinatorial exists, because the running "agent" is a combination of agent definitions, context, tool choice where you can modify each independently to create a new "agent"

I think Scion (Google's) does a decent job defining these concepts: https://googlecloudplatform.github.io/scion/concepts/