diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index d16cffca..45e748c6 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,3 +1,3 @@
 {
-  ".": "0.21.4"
+  ".": "0.21.5"
 }
\ No newline at end of file
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3feb9fd4..65dda387 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,19 @@
 # Changelog
 
+## 0.21.5 (2024-06-28)
+
+Full Changelog: [v0.21.4...v0.21.5](https://github.com/Finch-API/finch-api-python/compare/v0.21.4...v0.21.5)
+
+### Bug Fixes
+
+* **build:** include more files in sdist builds ([#409](https://github.com/Finch-API/finch-api-python/issues/409)) ([1508b49](https://github.com/Finch-API/finch-api-python/commit/1508b49756620d8fda71886beb750bc0bdc05d89))
+
+
+### Chores
+
+* **deps:** bump anyio to v4.4.0 ([#411](https://github.com/Finch-API/finch-api-python/issues/411)) ([45c5047](https://github.com/Finch-API/finch-api-python/commit/45c50471351af8213f414d60c269fbf3e2b4e4bd))
+* **internal:** add reflection helper function ([#412](https://github.com/Finch-API/finch-api-python/issues/412)) ([1e84873](https://github.com/Finch-API/finch-api-python/commit/1e848737d7505b57702604b8e95c3a8c85c75bc9))
+
 ## 0.21.4 (2024-06-26)
 
 Full Changelog: [v0.21.3...v0.21.4](https://github.com/Finch-API/finch-api-python/compare/v0.21.3...v0.21.4)
diff --git a/pyproject.toml b/pyproject.toml
index 70174cd2..47cc7b24 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "finch-api"
-version = "0.21.4"
+version = "0.21.5"
 description = "The official Python library for the Finch API"
 dynamic = ["readme"]
 license = "Apache-2.0"
@@ -99,6 +99,21 @@ include = [
 [tool.hatch.build.targets.wheel]
 packages = ["src/finch"]
 
+[tool.hatch.build.targets.sdist]
+# Basically everything except hidden files/directories (such as .github, .devcontainers, .python-version, etc)
+include = [
+  "/*.toml",
+  "/*.json",
+  "/*.lock",
+  "/*.md",
+  "/mypy.ini",
+  "/noxfile.py",
+  "bin/*",
+  "examples/*",
+  "src/*",
+  "tests/*",
+]
+
 [tool.hatch.metadata.hooks.fancy-pypi-readme]
 content-type = "text/markdown"
 
diff --git a/requirements-dev.lock b/requirements-dev.lock
index 08bf0559..1d784324 100644
--- a/requirements-dev.lock
+++ b/requirements-dev.lock
@@ -10,7 +10,7 @@
 -e file:.
 annotated-types==0.6.0
     # via pydantic
-anyio==4.1.0
+anyio==4.4.0
     # via finch-api
     # via httpx
 argcomplete==3.1.2
@@ -86,6 +86,7 @@ tomli==2.0.1
     # via mypy
     # via pytest
 typing-extensions==4.8.0
+    # via anyio
     # via finch-api
     # via mypy
     # via pydantic
diff --git a/requirements.lock b/requirements.lock
index ca7f06dd..22018417 100644
--- a/requirements.lock
+++ b/requirements.lock
@@ -10,7 +10,7 @@
 -e file:.
 annotated-types==0.6.0
     # via pydantic
-anyio==4.1.0
+anyio==4.4.0
     # via finch-api
     # via httpx
 certifi==2023.7.22
@@ -38,6 +38,7 @@ sniffio==1.3.0
     # via finch-api
     # via httpx
 typing-extensions==4.8.0
+    # via anyio
     # via finch-api
     # via pydantic
     # via pydantic-core
diff --git a/src/finch/_utils/__init__.py b/src/finch/_utils/__init__.py
index 667e2473..3efe66c8 100644
--- a/src/finch/_utils/__init__.py
+++ b/src/finch/_utils/__init__.py
@@ -49,4 +49,7 @@
     maybe_transform as maybe_transform,
     async_maybe_transform as async_maybe_transform,
 )
-from ._reflection import function_has_argument as function_has_argument
+from ._reflection import (
+    function_has_argument as function_has_argument,
+    assert_signatures_in_sync as assert_signatures_in_sync,
+)
diff --git a/src/finch/_utils/_reflection.py b/src/finch/_utils/_reflection.py
index e134f58e..9a53c7bd 100644
--- a/src/finch/_utils/_reflection.py
+++ b/src/finch/_utils/_reflection.py
@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import inspect
 from typing import Any, Callable
 
@@ -6,3 +8,35 @@ def function_has_argument(func: Callable[..., Any], arg_name: str) -> bool:
     """Returns whether or not the given function has a specific parameter"""
     sig = inspect.signature(func)
     return arg_name in sig.parameters
+
+
+def assert_signatures_in_sync(
+    source_func: Callable[..., Any],
+    check_func: Callable[..., Any],
+    *,
+    exclude_params: set[str] = set(),
+) -> None:
+    """Ensure that the signature of the second function matches the first."""
+
+    check_sig = inspect.signature(check_func)
+    source_sig = inspect.signature(source_func)
+
+    errors: list[str] = []
+
+    for name, source_param in source_sig.parameters.items():
+        if name in exclude_params:
+            continue
+
+        custom_param = check_sig.parameters.get(name)
+        if not custom_param:
+            errors.append(f"the `{name}` param is missing")
+            continue
+
+        if custom_param.annotation != source_param.annotation:
+            errors.append(
+                f"types for the `{name}` param are do not match; source={repr(source_param.annotation)} checking={repr(source_param.annotation)}"
+            )
+            continue
+
+    if errors:
+        raise AssertionError(f"{len(errors)} errors encountered when comparing signatures:\n\n" + "\n\n".join(errors))
diff --git a/src/finch/_version.py b/src/finch/_version.py
index b2617b10..da53b920 100644
--- a/src/finch/_version.py
+++ b/src/finch/_version.py
@@ -1,4 +1,4 @@
 # File generated from our OpenAPI spec by Stainless. See CONTRIBUTING.md for details.
 
 __title__ = "finch"
-__version__ = "0.21.4"  # x-release-please-version
+__version__ = "0.21.5"  # x-release-please-version