diff --git a/pyproject.toml b/pyproject.toml
index 265ac8e4..a5122880 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -53,7 +53,6 @@ dev-dependencies = [
     "pytest",
     "pytest-asyncio",
     "ruff",
-    "isort",
     "time-machine",
     "nox",
     "dirty-equals>=0.6.0",
@@ -66,7 +65,6 @@ format = { chain = [
   "format:ruff",
   "format:docs",
   "fix:ruff",
-  "format:isort",
 ]}
 "format:black" = "black ."
 "format:docs" = "python bin/ruffen-docs.py README.md api.md"
@@ -127,16 +125,13 @@ reportImplicitOverride = true
 reportImportCycles = false
 reportPrivateUsage = false
 
-[tool.isort]
-profile = "black"
-length_sort = true
-extra_standard_library = ["typing_extensions"]
-
 [tool.ruff]
 line-length = 120
 output-format = "grouped"
 target-version = "py37"
 select = [
+  # isort
+  "I",
   # bugbear rules
   "B",
   # remove unused imports
@@ -163,6 +158,13 @@ ignore-init-module-imports = true
 [tool.ruff.format]
 docstring-code-format = true
 
+[tool.ruff.lint.isort]
+length-sort = true
+length-sort-straight = true
+combine-as-imports = true
+extra-standard-library = ["typing_extensions"]
+known-first-party = ["anthropic", "tests"]
+
 [tool.ruff.per-file-ignores]
 "bin/**.py" = ["T201", "T203"]
 "tests/**.py" = ["T201", "T203"]
diff --git a/requirements-dev.lock b/requirements-dev.lock
index 59453708..8ff81764 100644
--- a/requirements-dev.lock
+++ b/requirements-dev.lock
@@ -27,7 +27,6 @@ huggingface-hub==0.16.4
 idna==3.4
 importlib-metadata==7.0.0
 iniconfig==2.0.0
-isort==5.10.1
 mypy==1.7.1
 mypy-extensions==1.0.0
 nodeenv==1.8.0
diff --git a/src/anthropic/__init__.py b/src/anthropic/__init__.py
index 6ea55b0b..c1e6bd4c 100644
--- a/src/anthropic/__init__.py
+++ b/src/anthropic/__init__.py
@@ -15,8 +15,7 @@
     RequestOptions,
 )
 from ._version import __title__, __version__
-from ._constants import AI_PROMPT as AI_PROMPT
-from ._constants import HUMAN_PROMPT as HUMAN_PROMPT
+from ._constants import AI_PROMPT as AI_PROMPT, HUMAN_PROMPT as HUMAN_PROMPT
 from ._exceptions import (
     APIError,
     ConflictError,
diff --git a/src/anthropic/_client.py b/src/anthropic/_client.py
index 2785e7c6..fea68224 100644
--- a/src/anthropic/_client.py
+++ b/src/anthropic/_client.py
@@ -21,13 +21,18 @@
     AsyncTransport,
     RequestOptions,
 )
-from ._utils import is_given, get_async_library
+from ._utils import (
+    is_given,
+    get_async_library,
+)
 from ._version import __version__
-from ._streaming import Stream as Stream
-from ._streaming import AsyncStream as AsyncStream
+from ._streaming import Stream as Stream, AsyncStream as AsyncStream
 from ._exceptions import APIStatusError
-from ._tokenizers import TokenizerType  # type: ignore[import]
-from ._tokenizers import sync_get_tokenizer, async_get_tokenizer
+from ._tokenizers import (
+    TokenizerType,  # type: ignore[import]
+    sync_get_tokenizer,
+    async_get_tokenizer,
+)
 from ._base_client import (
     DEFAULT_LIMITS,
     DEFAULT_MAX_RETRIES,
diff --git a/src/anthropic/_compat.py b/src/anthropic/_compat.py
index 34323c9b..d95db8ed 100644
--- a/src/anthropic/_compat.py
+++ b/src/anthropic/_compat.py
@@ -43,21 +43,23 @@ def is_typeddict(type_: type[Any]) -> bool:  # noqa: ARG001
 
 else:
     if PYDANTIC_V2:
-        from pydantic.v1.typing import get_args as get_args
-        from pydantic.v1.typing import is_union as is_union
-        from pydantic.v1.typing import get_origin as get_origin
-        from pydantic.v1.typing import is_typeddict as is_typeddict
-        from pydantic.v1.typing import is_literal_type as is_literal_type
-        from pydantic.v1.datetime_parse import parse_date as parse_date
-        from pydantic.v1.datetime_parse import parse_datetime as parse_datetime
+        from pydantic.v1.typing import (
+            get_args as get_args,
+            is_union as is_union,
+            get_origin as get_origin,
+            is_typeddict as is_typeddict,
+            is_literal_type as is_literal_type,
+        )
+        from pydantic.v1.datetime_parse import parse_date as parse_date, parse_datetime as parse_datetime
     else:
-        from pydantic.typing import get_args as get_args
-        from pydantic.typing import is_union as is_union
-        from pydantic.typing import get_origin as get_origin
-        from pydantic.typing import is_typeddict as is_typeddict
-        from pydantic.typing import is_literal_type as is_literal_type
-        from pydantic.datetime_parse import parse_date as parse_date
-        from pydantic.datetime_parse import parse_datetime as parse_datetime
+        from pydantic.typing import (
+            get_args as get_args,
+            is_union as is_union,
+            get_origin as get_origin,
+            is_typeddict as is_typeddict,
+            is_literal_type as is_literal_type,
+        )
+        from pydantic.datetime_parse import parse_date as parse_date, parse_datetime as parse_datetime
 
 
 # refactored config
diff --git a/src/anthropic/_models.py b/src/anthropic/_models.py
index 330a2064..48d5624f 100644
--- a/src/anthropic/_models.py
+++ b/src/anthropic/_models.py
@@ -30,17 +30,11 @@
     AnyMapping,
     HttpxRequestFiles,
 )
-from ._utils import (
-    is_list,
-    is_given,
-    is_mapping,
-    parse_date,
-    parse_datetime,
-    strip_not_given,
-)
-from ._compat import PYDANTIC_V2, ConfigDict
-from ._compat import GenericModel as BaseGenericModel
+from ._utils import is_list, is_given, is_mapping, parse_date, parse_datetime, strip_not_given
 from ._compat import (
+    PYDANTIC_V2,
+    ConfigDict,
+    GenericModel as BaseGenericModel,
     get_args,
     is_union,
     parse_obj,
diff --git a/src/anthropic/_types.py b/src/anthropic/_types.py
index 1f8283fa..1e6e8770 100644
--- a/src/anthropic/_types.py
+++ b/src/anthropic/_types.py
@@ -19,14 +19,7 @@
     Sequence,
     AsyncIterator,
 )
-from typing_extensions import (
-    Literal,
-    Protocol,
-    TypeAlias,
-    TypedDict,
-    override,
-    runtime_checkable,
-)
+from typing_extensions import Literal, Protocol, TypeAlias, TypedDict, override, runtime_checkable
 
 import httpx
 import pydantic
diff --git a/src/anthropic/_utils/__init__.py b/src/anthropic/_utils/__init__.py
index a43201d3..2dcfc122 100644
--- a/src/anthropic/_utils/__init__.py
+++ b/src/anthropic/_utils/__init__.py
@@ -1,40 +1,45 @@
 from ._proxy import LazyProxy as LazyProxy
-from ._utils import flatten as flatten
-from ._utils import is_dict as is_dict
-from ._utils import is_list as is_list
-from ._utils import is_given as is_given
-from ._utils import is_tuple as is_tuple
-from ._utils import is_mapping as is_mapping
-from ._utils import is_tuple_t as is_tuple_t
-from ._utils import parse_date as parse_date
-from ._utils import is_sequence as is_sequence
-from ._utils import coerce_float as coerce_float
-from ._utils import is_mapping_t as is_mapping_t
-from ._utils import removeprefix as removeprefix
-from ._utils import removesuffix as removesuffix
-from ._utils import extract_files as extract_files
-from ._utils import is_sequence_t as is_sequence_t
-from ._utils import required_args as required_args
-from ._utils import coerce_boolean as coerce_boolean
-from ._utils import coerce_integer as coerce_integer
-from ._utils import file_from_path as file_from_path
-from ._utils import parse_datetime as parse_datetime
-from ._utils import strip_not_given as strip_not_given
-from ._utils import deepcopy_minimal as deepcopy_minimal
-from ._utils import get_async_library as get_async_library
-from ._utils import maybe_coerce_float as maybe_coerce_float
-from ._utils import get_required_header as get_required_header
-from ._utils import maybe_coerce_boolean as maybe_coerce_boolean
-from ._utils import maybe_coerce_integer as maybe_coerce_integer
-from ._typing import is_list_type as is_list_type
-from ._typing import is_union_type as is_union_type
-from ._typing import extract_type_arg as extract_type_arg
-from ._typing import is_required_type as is_required_type
-from ._typing import is_annotated_type as is_annotated_type
-from ._typing import strip_annotated_type as strip_annotated_type
-from ._typing import extract_type_var_from_base as extract_type_var_from_base
-from ._streams import consume_sync_iterator as consume_sync_iterator
-from ._streams import consume_async_iterator as consume_async_iterator
-from ._transform import PropertyInfo as PropertyInfo
-from ._transform import transform as transform
-from ._transform import maybe_transform as maybe_transform
+from ._utils import (
+    flatten as flatten,
+    is_dict as is_dict,
+    is_list as is_list,
+    is_given as is_given,
+    is_tuple as is_tuple,
+    is_mapping as is_mapping,
+    is_tuple_t as is_tuple_t,
+    parse_date as parse_date,
+    is_sequence as is_sequence,
+    coerce_float as coerce_float,
+    is_mapping_t as is_mapping_t,
+    removeprefix as removeprefix,
+    removesuffix as removesuffix,
+    extract_files as extract_files,
+    is_sequence_t as is_sequence_t,
+    required_args as required_args,
+    coerce_boolean as coerce_boolean,
+    coerce_integer as coerce_integer,
+    file_from_path as file_from_path,
+    parse_datetime as parse_datetime,
+    strip_not_given as strip_not_given,
+    deepcopy_minimal as deepcopy_minimal,
+    get_async_library as get_async_library,
+    maybe_coerce_float as maybe_coerce_float,
+    get_required_header as get_required_header,
+    maybe_coerce_boolean as maybe_coerce_boolean,
+    maybe_coerce_integer as maybe_coerce_integer,
+)
+from ._typing import (
+    is_list_type as is_list_type,
+    is_union_type as is_union_type,
+    extract_type_arg as extract_type_arg,
+    is_required_type as is_required_type,
+    is_annotated_type as is_annotated_type,
+    strip_annotated_type as strip_annotated_type,
+    extract_type_var_from_base as extract_type_var_from_base,
+)
+from ._streams import consume_sync_iterator as consume_sync_iterator, consume_async_iterator as consume_async_iterator
+from ._transform import (
+    PropertyInfo as PropertyInfo,
+    transform as transform,
+    maybe_transform as maybe_transform,
+)
diff --git a/src/anthropic/_utils/_transform.py b/src/anthropic/_utils/_transform.py
index 342b5241..3a1c1496 100644
--- a/src/anthropic/_utils/_transform.py
+++ b/src/anthropic/_utils/_transform.py
@@ -6,7 +6,10 @@
 
 import pydantic
 
-from ._utils import is_list, is_mapping
+from ._utils import (
+    is_list,
+    is_mapping,
+)
 from ._typing import (
     is_list_type,
     is_union_type,
diff --git a/src/anthropic/_utils/_utils.py b/src/anthropic/_utils/_utils.py
index cc624b0c..1c5c21a8 100644
--- a/src/anthropic/_utils/_utils.py
+++ b/src/anthropic/_utils/_utils.py
@@ -21,8 +21,7 @@
 import sniffio
 
 from .._types import Headers, NotGiven, FileTypes, NotGivenOr, HeadersLike
-from .._compat import parse_date as parse_date
-from .._compat import parse_datetime as parse_datetime
+from .._compat import parse_date as parse_date, parse_datetime as parse_datetime
 
 _T = TypeVar("_T")
 _TupleT = TypeVar("_TupleT", bound=Tuple[object, ...])
diff --git a/src/anthropic/lib/streaming/__init__.py b/src/anthropic/lib/streaming/__init__.py
index 642cc33a..71c5efd6 100644
--- a/src/anthropic/lib/streaming/__init__.py
+++ b/src/anthropic/lib/streaming/__init__.py
@@ -1,6 +1,8 @@
-from ._messages import MessageStream as MessageStream
-from ._messages import MessageStreamT as MessageStreamT
-from ._messages import AsyncMessageStream as AsyncMessageStream
-from ._messages import AsyncMessageStreamT as AsyncMessageStreamT
-from ._messages import MessageStreamManager as MessageStreamManager
-from ._messages import AsyncMessageStreamManager as AsyncMessageStreamManager
+from ._messages import (
+    MessageStream as MessageStream,
+    MessageStreamT as MessageStreamT,
+    AsyncMessageStream as AsyncMessageStream,
+    AsyncMessageStreamT as AsyncMessageStreamT,
+    MessageStreamManager as MessageStreamManager,
+    AsyncMessageStreamManager as AsyncMessageStreamManager,
+)
diff --git a/src/anthropic/resources/__init__.py b/src/anthropic/resources/__init__.py
index c47cc0e9..d39ac2ed 100644
--- a/src/anthropic/resources/__init__.py
+++ b/src/anthropic/resources/__init__.py
@@ -1,12 +1,7 @@
 # File generated from our OpenAPI spec by Stainless.
 
 from .beta import Beta, AsyncBeta, BetaWithRawResponse, AsyncBetaWithRawResponse
-from .completions import (
-    Completions,
-    AsyncCompletions,
-    CompletionsWithRawResponse,
-    AsyncCompletionsWithRawResponse,
-)
+from .completions import Completions, AsyncCompletions, CompletionsWithRawResponse, AsyncCompletionsWithRawResponse
 
 __all__ = [
     "Completions",
diff --git a/src/anthropic/resources/beta/__init__.py b/src/anthropic/resources/beta/__init__.py
index aae168a4..ef10de5d 100644
--- a/src/anthropic/resources/beta/__init__.py
+++ b/src/anthropic/resources/beta/__init__.py
@@ -1,12 +1,7 @@
 # File generated from our OpenAPI spec by Stainless.
 
 from .beta import Beta, AsyncBeta, BetaWithRawResponse, AsyncBetaWithRawResponse
-from .messages import (
-    Messages,
-    AsyncMessages,
-    MessagesWithRawResponse,
-    AsyncMessagesWithRawResponse,
-)
+from .messages import Messages, AsyncMessages, MessagesWithRawResponse, AsyncMessagesWithRawResponse
 
 __all__ = [
     "Messages",
diff --git a/src/anthropic/resources/beta/beta.py b/src/anthropic/resources/beta/beta.py
index 5d472172..823e9669 100644
--- a/src/anthropic/resources/beta/beta.py
+++ b/src/anthropic/resources/beta/beta.py
@@ -4,12 +4,7 @@
 
 from typing import TYPE_CHECKING
 
-from .messages import (
-    Messages,
-    AsyncMessages,
-    MessagesWithRawResponse,
-    AsyncMessagesWithRawResponse,
-)
+from .messages import Messages, AsyncMessages, MessagesWithRawResponse, AsyncMessagesWithRawResponse
 from ..._resource import SyncAPIResource, AsyncAPIResource
 
 if TYPE_CHECKING:
diff --git a/src/anthropic/resources/beta/messages.py b/src/anthropic/resources/beta/messages.py
index 5a516622..18c524c3 100644
--- a/src/anthropic/resources/beta/messages.py
+++ b/src/anthropic/resources/beta/messages.py
@@ -8,7 +8,13 @@
 
 import httpx
 
-from ..._types import NOT_GIVEN, Body, Query, Headers, NotGiven
+from ..._types import (
+    NOT_GIVEN,
+    Body,
+    Query,
+    Headers,
+    NotGiven,
+)
 from ..._utils import required_args, maybe_transform
 from ..._resource import SyncAPIResource, AsyncAPIResource
 from ..._response import to_raw_response_wrapper, async_to_raw_response_wrapper
@@ -19,7 +25,9 @@
     MessageStreamEvent,
     message_create_params,
 )
-from ..._base_client import make_request_options
+from ..._base_client import (
+    make_request_options,
+)
 from ...lib.streaming import (
     MessageStream,
     MessageStreamT,
diff --git a/src/anthropic/resources/completions.py b/src/anthropic/resources/completions.py
index 17916130..d78ac436 100644
--- a/src/anthropic/resources/completions.py
+++ b/src/anthropic/resources/completions.py
@@ -8,12 +8,20 @@
 import httpx
 
 from ..types import Completion, completion_create_params
-from .._types import NOT_GIVEN, Body, Query, Headers, NotGiven
+from .._types import (
+    NOT_GIVEN,
+    Body,
+    Query,
+    Headers,
+    NotGiven,
+)
 from .._utils import required_args, maybe_transform
 from .._resource import SyncAPIResource, AsyncAPIResource
 from .._response import to_raw_response_wrapper, async_to_raw_response_wrapper
 from .._streaming import Stream, AsyncStream
-from .._base_client import make_request_options
+from .._base_client import (
+    make_request_options,
+)
 
 if TYPE_CHECKING:
     from .._client import Anthropic, AsyncAnthropic
diff --git a/tests/test_client.py b/tests/test_client.py
index 2fe4afe6..53bc3cc5 100644
--- a/tests/test_client.py
+++ b/tests/test_client.py
@@ -21,11 +21,7 @@
 from anthropic._client import Anthropic, AsyncAnthropic
 from anthropic._models import BaseModel, FinalRequestOptions
 from anthropic._streaming import Stream, AsyncStream
-from anthropic._exceptions import (
-    APIStatusError,
-    APITimeoutError,
-    APIResponseValidationError,
-)
+from anthropic._exceptions import APIStatusError, APITimeoutError, APIResponseValidationError
 from anthropic._base_client import (
     DEFAULT_TIMEOUT,
     HTTPX_DEFAULT_TIMEOUT,
diff --git a/tests/utils.py b/tests/utils.py
index 3a5830b4..4c9df902 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -8,7 +8,12 @@
 from typing_extensions import Literal, get_args, get_origin, assert_type
 
 from anthropic._types import NoneType
-from anthropic._utils import is_dict, is_list, is_list_type, is_union_type
+from anthropic._utils import (
+    is_dict,
+    is_list,
+    is_list_type,
+    is_union_type,
+)
 from anthropic._compat import PYDANTIC_V2, field_outer_type, get_model_fields
 from anthropic._models import BaseModel