diff --git a/CHANGELOG.md b/CHANGELOG.md
index 353312e6c8..63fb5d4278 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,8 +8,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 ### Changed
 
+- Pydantic field type validation has been improved.
 - Moved `quacc.custodian` to `quacc.calculators.custodian`
-- Renamed `quacc.thermo.ideal_gas` to `quacc.thermo.run_ideal_gas`
+- Moved `quacc.utils.thermo.ideal_gas` to `quacc.builders.thermo.build_ideal_gas`
 - Renamed `quacc.schemas.ase.summarize_thermo` to `quacc.schemas.ase.summarize_igt_thermo`
 
 ## [0.3.0]
diff --git a/src/quacc/_cli/__init__.py b/src/quacc/_cli/__init__.py
index edb7cddd52..e5aa1804c9 100644
--- a/src/quacc/_cli/__init__.py
+++ b/src/quacc/_cli/__init__.py
@@ -1 +1 @@
-"""Command line interface"""
+"""Command line interface for quacc."""
diff --git a/src/quacc/builders/__init__.py b/src/quacc/builders/__init__.py
new file mode 100644
index 0000000000..6e1cccb7f2
--- /dev/null
+++ b/src/quacc/builders/__init__.py
@@ -0,0 +1,6 @@
+"""
+Modules related to builders, which take in an output from at least one calculation and collate/analyze the data to
+produce valuable derived properties. Builders do not call a compute-intensive (e.g. DFT) executable. Rather,
+they are manipulations on pre-computed data. Most commonly, this is a many-to-one transformation, and the
+builders can be run independently of the recipes if desired.
+"""
diff --git a/src/quacc/runners/thermo.py b/src/quacc/builders/thermo.py
similarity index 99%
rename from src/quacc/runners/thermo.py
rename to src/quacc/builders/thermo.py
index 81bcf7d8c2..f1b10da50a 100644
--- a/src/quacc/runners/thermo.py
+++ b/src/quacc/builders/thermo.py
@@ -15,7 +15,7 @@
     from ase import Atoms
 
 
-def run_ideal_gas(
+def build_ideal_gas(
     atoms: Atoms,
     vib_freqs: list[float | complex],
     energy: float = 0.0,
diff --git a/src/quacc/calculators/presets/__init__.py b/src/quacc/calculators/presets/__init__.py
index e5cbc93fe3..4a9155d031 100644
--- a/src/quacc/calculators/presets/__init__.py
+++ b/src/quacc/calculators/presets/__init__.py
@@ -1 +1 @@
-"""Presets for various calculators"""
+"""Preset parameters for select calculators"""
diff --git a/src/quacc/recipes/lj/core.py b/src/quacc/recipes/lj/core.py
index 3382c559d3..883a24e534 100644
--- a/src/quacc/recipes/lj/core.py
+++ b/src/quacc/recipes/lj/core.py
@@ -11,8 +11,8 @@
 from ase.optimize import FIRE
 
 from quacc import job
+from quacc.builders.thermo import build_ideal_gas
 from quacc.runners.calc import run_ase_opt, run_ase_vib, run_calc
-from quacc.runners.thermo import run_ideal_gas
 from quacc.schemas import fetch_atoms
 from quacc.schemas.ase import (
     summarize_igt_thermo,
@@ -183,7 +183,7 @@ def freq_job(
         vibrations, additional_fields={"name": "LJ Frequency"}
     )
 
-    igt = run_ideal_gas(atoms, vibrations.get_frequencies(), energy=energy)
+    igt = build_ideal_gas(atoms, vibrations.get_frequencies(), energy=energy)
     vib_summary["thermo"] = summarize_igt_thermo(
         igt,
         temperature=temperature,
diff --git a/src/quacc/recipes/newtonnet/core.py b/src/quacc/recipes/newtonnet/core.py
index 90d3bba0ef..759d099b86 100644
--- a/src/quacc/recipes/newtonnet/core.py
+++ b/src/quacc/recipes/newtonnet/core.py
@@ -10,8 +10,8 @@
 from monty.dev import requires
 
 from quacc import SETTINGS, job
+from quacc.builders.thermo import build_ideal_gas
 from quacc.runners.calc import run_ase_opt, run_calc
-from quacc.runners.thermo import run_ideal_gas
 from quacc.schemas import fetch_atoms
 from quacc.schemas.ase import (
     summarize_igt_thermo,
@@ -225,7 +225,7 @@ def freq_job(
         vib, additional_fields={"name": "ASE Vibrations Analysis"}
     )
 
-    igt = run_ideal_gas(final_atoms, vib.get_frequencies(), energy=energy)
+    igt = build_ideal_gas(final_atoms, vib.get_frequencies(), energy=energy)
     summary["thermo"] = summarize_igt_thermo(
         igt,
         temperature=temperature,
diff --git a/src/quacc/recipes/tblite/core.py b/src/quacc/recipes/tblite/core.py
index 72530c07a2..abe7e4fef4 100644
--- a/src/quacc/recipes/tblite/core.py
+++ b/src/quacc/recipes/tblite/core.py
@@ -7,8 +7,8 @@
 from monty.dev import requires
 
 from quacc import job
+from quacc.builders.thermo import build_ideal_gas
 from quacc.runners.calc import run_ase_opt, run_ase_vib, run_calc
-from quacc.runners.thermo import run_ideal_gas
 from quacc.schemas import fetch_atoms
 from quacc.schemas.ase import (
     summarize_igt_thermo,
@@ -210,7 +210,7 @@ def freq_job(
         vibrations, additional_fields={"name": "TBLite Frequency"}
     )
 
-    igt = run_ideal_gas(atoms, vibrations.get_frequencies(), energy=energy)
+    igt = build_ideal_gas(atoms, vibrations.get_frequencies(), energy=energy)
     vib_summary["thermo"] = summarize_igt_thermo(
         igt,
         temperature=temperature,
diff --git a/src/quacc/runners/__init__.py b/src/quacc/runners/__init__.py
index d79d60910d..81d0120b2f 100644
--- a/src/quacc/runners/__init__.py
+++ b/src/quacc/runners/__init__.py
@@ -1,3 +1 @@
-"""
-Various utility functions for running ASE calculations.
-"""
+"""Utility functions for preparing and running recipes."""
diff --git a/src/quacc/schemas/__init__.py b/src/quacc/schemas/__init__.py
index 1179395058..a6aaec45a0 100644
--- a/src/quacc/schemas/__init__.py
+++ b/src/quacc/schemas/__init__.py
@@ -1,4 +1,4 @@
-"""Schemas for storing data from recipes"""
+"""Schemas for curating the output data from recipes"""
 
 from quacc.schemas.atoms import fetch_atoms
 
diff --git a/src/quacc/utils/__init__.py b/src/quacc/utils/__init__.py
index a1906f971f..c645add046 100644
--- a/src/quacc/utils/__init__.py
+++ b/src/quacc/utils/__init__.py
@@ -1,6 +1,5 @@
-"""
-Various utility functions
-"""
+"""Miscellaneous utility functions"""
+
 from quacc.utils.atoms import check_charge_and_spin
 
 __all__ = ["check_charge_and_spin"]
diff --git a/src/quacc/wflow/__init__.py b/src/quacc/wflow/__init__.py
index eae43ded1e..8801d37fb6 100644
--- a/src/quacc/wflow/__init__.py
+++ b/src/quacc/wflow/__init__.py
@@ -1,3 +1 @@
-"""
-Various utility functions for workflow management
-"""
+"""Modules related to workflow management"""
diff --git a/tests/runners/test_thermo.py b/tests/runners/test_thermo.py
index b120e524e1..da471ee64c 100644
--- a/tests/runners/test_thermo.py
+++ b/tests/runners/test_thermo.py
@@ -3,24 +3,24 @@
 from ase.calculators.emt import EMT
 from ase.units import invcm
 
-from quacc.runners.thermo import run_ideal_gas
+from quacc.builders.thermo import build_ideal_gas
 
 
-def test_run_ideal_gas():
+def test_build_ideal_gas():
     co2 = molecule("CO2")
-    igt = run_ideal_gas(co2, [526, 526, 1480, 2565], spin_multiplicity=2)
+    igt = build_ideal_gas(co2, [526, 526, 1480, 2565], spin_multiplicity=2)
     assert igt.geometry == "linear"
     assert igt.spin == 0.5
 
     co2 = molecule("CO2")
     co2.calc = EMT()
     co2.calc.results["magmom"] = 1.0
-    igt = run_ideal_gas(co2, [526, 526, 1480, 2565])
+    igt = build_ideal_gas(co2, [526, 526, 1480, 2565])
     assert igt.spin == 0.5
     assert igt.get_ZPE_correction() == pytest.approx(2548.5 * invcm)
 
     co2 = molecule("CO2")
     co2.calc = EMT()
     co2.calc.results["magmom"] = 1.0
-    igt = run_ideal_gas(co2, [-12, 526, 526, 1480, 2565])
+    igt = build_ideal_gas(co2, [-12, 526, 526, 1480, 2565])
     assert igt.get_ZPE_correction() == pytest.approx(2548.5 * invcm)