Type Alias BuilderApi<InputType, OutputType, Added, DynamicUnion>

type BuilderApi<
    InputType extends Record<string, unknown>,
    OutputType,
    Added extends keyof InputType,
    DynamicUnion extends keyof InputType,
> = {
    build: (
        ...args: Exclude<DynamicUnion, Added> extends never
            ? []
            : [
                build_not_allowed_because_not_all_dynamic_fields_were_specified: never,
            ],
    ) => Exclude<DynamicUnion, Added> extends never
        ? Tool2Agent<DynamicInputType<InputType, DynamicUnion>, OutputType>
        : never;
    field: <
        FieldName extends Exclude<DynamicUnion, Added>,
        Requirements extends readonly Exclude<DynamicUnion, FieldName>[],
    >(
        key: FieldName,
        cfg: ToolFieldConfig<
            InputType,
            FieldName,
            Requirements,
            Exclude<keyof InputType, DynamicUnion | FieldName>,
        >,
    ) => BuilderApi<InputType, OutputType, Added | FieldName, DynamicUnion>;
    spec: ToolSpec<Pick<InputType, DynamicUnion>>;
}