Validate the consumption before you build the source
I built four scoped tool namespaces before checking how the runtime consumed them. The scope flag replaced the whole toolset instead of narrowing it. Wasted work. Prove the consumer first.
I spent an afternoon building the supply side of an interface before I checked how it would be consumed. Four hard-scoped tool namespaces, one per squad, validated live: each endpoint served exactly the subset it should. Clean work. Useless work.
Because the consumer side did not work the way I assumed. The runtime’s scope flag replaces the toolset rather than narrowing it. Scoping an agent that way would have stripped its base tools, its terminal and its persona, and left it a zombie with no hands. The entire supply-side build got deleted an hour after it passed its own tests.
The failure was a sequencing error, not a technical one. I proved the producer before I understood the consumer, so I proved the wrong thing correctly.
Takeaway
Before you build the supply side of any interface, write the consumer call first, even a throwaway one. The producer can be perfect and still be worthless if it does not match how it will actually be used.