Raised at compile time when Claudex.Tool can't turn a @spec argument
type into a JSON schema — a typespec construct Claudex doesn't map (a
function type, a bare pid(), an unrecognized Ecto field type, ...), or
a Mod.t() reference that isn't a loaded struct or Ecto schema.
Fix the @spec, or skip type inference for that tool entirely by
passing args_schema: in the @tool options — when it's set, the
@spec is never even inspected, so nothing here can raise.