From 14d838cc69824deb96586f37c5b3cbbb8b9e4c77 Mon Sep 17 00:00:00 2001
From: breken-ai <312387581+breken-ai@users.noreply.github.com>
Date: Fri, 25 Sep 2026 21:17:44 -0700
Subject: [PATCH] utils: resolve string annotations when converting functions
 to tools

Under `from __future__ import annotations`, or with quoted annotations,
every parameter annotation is a string. convert_function_to_tool passed
those strings to a pydantic model built inside ollama._utils, which
cannot resolve names like Optional or Literal from the caller's module,
so chat(tools=[func]) raised PydanticUserError before sending anything.

Evaluate the annotations with get_type_hints in the function's own
module and fall back to the raw annotation if that fails.
---
 ollama/_utils.py    | 21 ++++++++++++++++++++-
 tests/test_utils.py | 20 +++++++++++++++++++-
 2 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/ollama/_utils.py b/ollama/_utils.py
index 15f1cc0c..53047659 100644
--- a/ollama/_utils.py
+++ b/ollama/_utils.py
@@ -6,6 +6,7 @@
 from typing import Callable, Union
 
 import pydantic
+from typing_extensions import get_type_hints
 
 from ollama._types import Tool
 
@@ -53,14 +54,32 @@ def _parse_docstring(doc_string: Union[str, None]) -> dict[str, str]:
   return parsed_docstring
 
 
+def _resolve_type_hints(func: Callable) -> dict:
+  # String annotations (quoted, or under `from __future__ import annotations`) name types
+  # from the function's module, which pydantic cannot see from here, so evaluate them there.
+  try:
+    return get_type_hints(inspect.unwrap(func), include_extras=True)
+  except Exception:
+    return {}
+
+
+def _parameter_annotation(name: str, parameter: inspect.Parameter, type_hints: dict):
+  if parameter.annotation is inspect.Parameter.empty:
+    return str
+  if isinstance(parameter.annotation, str):
+    return type_hints.get(name, parameter.annotation)
+  return parameter.annotation
+
+
 def convert_function_to_tool(func: Callable) -> Tool:
   doc_string_hash = str(hash(inspect.getdoc(func)))
   parsed_docstring = _parse_docstring(inspect.getdoc(func))
+  type_hints = _resolve_type_hints(func)
   schema = type(
     func.__name__,
     (pydantic.BaseModel,),
     {
-      '__annotations__': {k: v.annotation if v.annotation != inspect._empty else str for k, v in inspect.signature(func).parameters.items()},
+      '__annotations__': {k: _parameter_annotation(k, v, type_hints) for k, v in inspect.signature(func).parameters.items()},
       '__signature__': inspect.signature(func),
       '__doc__': parsed_docstring[doc_string_hash],
     },
diff --git a/tests/test_utils.py b/tests/test_utils.py
index cb9e0d4f..baf80284 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -1,6 +1,6 @@
 import json
 import sys
-from typing import Dict, List, Mapping, Sequence, Set, Tuple, Union
+from typing import Dict, List, Literal, Mapping, Optional, Sequence, Set, Tuple, Union
 
 from ollama._utils import convert_function_to_tool
 
@@ -256,3 +256,21 @@ def func_with_parentheses_and_args(a: int, b: int):
   tool = convert_function_to_tool(func_with_parentheses_and_args).model_dump()
   assert tool['function']['parameters']['properties']['a']['description'] == 'First (:thing) number to add'
   assert tool['function']['parameters']['properties']['b']['description'] == 'Second number to add'
+
+
+def test_function_with_string_annotations():
+  # Annotations are strings under `from __future__ import annotations`, or when quoted.
+  def get_weather(city: 'str', unit: "Literal['celsius', 'fahrenheit']", days: 'Optional[int]' = None) -> 'str':
+    """
+    Get the weather for a city.
+    Args:
+        city: The city
+        unit: The unit
+        days: Number of days
+    """
+
+  tool = convert_function_to_tool(get_weather).model_dump()
+  assert tool['function']['parameters']['properties']['city']['type'] == 'string'
+  assert tool['function']['parameters']['properties']['unit']['type'] == 'string'
+  assert tool['function']['parameters']['properties']['days']['type'] == 'integer'
+  assert tool['function']['parameters']['required'] == ['city', 'unit']