[DZH166]

Problem

CreateChatCompletion builds the response schema with two mutually recursive helpers:

def _build_parameters(self):
    if ...: return self._create_type_schema(tp)     # fallback
def _create_type_schema(self, tp):
    if ...: return self._build_parameters()          # fallback

_create_type_schema() only handles list, dict and Union; every other generic alias falls back to _build_parameters(), which falls back again - with no terminating branch. A perfectly normal structured-output type therefore crashes while the tool schema is built in __init__:

typing.Literal['yes','no'] -> RecursionError: maximum recursion depth exceeded
typing.Set[int]            -> RecursionError
typing.Tuple[int, str]     -> RecursionError

Literal is a standard structured-output response type and nothing validates or rejects it (the constructor signature is response_type: Optional[Type] = str).

Fix

For generics that are not list/dict/Union, build the schema from the origin type instead of recursing (Literal[...] → its value type, Set[int]/Tuple[...] → array), so every accepted annotation terminates.

Tests

tests/tools (17 passed): parametrised Literal, Set, Tuple, frozenset all build a schema with response required.

pytest tests/tools -q    # before: 4 failed, 9 passed (new file)   after: 17 passed