Boundary
Hosts now depend on a tool schema and method names. The adapter owns the translation into the underlying wrapper.
What this adds
Separate tool use from process details.
The wrapper from lab 02 already gives you structured results. This lab adds discovery and invocation over a small protocol surface: list the tools, then call one by name with structured arguments.
This is the same boundary real hosts rely on when they do not want to hard-code per-tool shell knowledge.
Done when
A separate client can list available tools and invoke one without knowing any of the original shell arguments.
Real-world analog
Model Context Protocol is the direct analog: a host discovers tool shapes and uses them through a protocol boundary instead of shell trivia.
Read alongside it
The larger background lives on the protocols page.