Once a model has chosen a tool, one artifact decides whether the resulting call is any good: the input schema. It is read at two different moments by two different readers. The model reads it while it writes the arguments, and your system reads it when it decides whether to accept them. Most teams design a schema entirely for the second…

When an agent reaches for the wrong tool, the instinct is to inspect the code: a broken function, a malformed schema, a name that should have been clearer. Almost none of that touched the decision. By the time any tool executes, the model has already settled on it, and it settled by reading natural language. The thing that actually drove the choice is the…