diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 19d3fac..022fdcb 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -44,6 +44,9 @@ jobs:
           uv run poe tests
           uv run poe tests-report
 
+      - name: Static type check
+        run: uv run poe type-check
+
       - name: Upload coverage reports to Codecov
         uses: codecov/codecov-action@v5
         with:
diff --git a/jambo/parser/_type_parser.py b/jambo/parser/_type_parser.py
index 080965c..cce8042 100644
--- a/jambo/parser/_type_parser.py
+++ b/jambo/parser/_type_parser.py
@@ -1,16 +1,16 @@
-from jambo.types.type_parser_options import TypeParserOptions
+from jambo.types.type_parser_options import JSONSchema, TypeParserOptions
 
 from pydantic import Field, TypeAdapter
-from typing_extensions import Annotated, Any, Generic, Self, TypeVar, Unpack
+from typing_extensions import Annotated, Any, ClassVar, Generic, Self, TypeVar, Unpack
 
 from abc import ABC, abstractmethod
 
 
-T = TypeVar("T")
+T = TypeVar("T", bound=type)
 
 
 class GenericTypeParser(ABC, Generic[T]):
-    json_schema_type: str = None
+    json_schema_type: ClassVar[str]
 
     type_mappings: dict[str, str] = {}
 
@@ -21,7 +21,7 @@ class GenericTypeParser(ABC, Generic[T]):
 
     @abstractmethod
     def from_properties_impl(
-        self, name: str, properties: dict[str, Any], **kwargs: Unpack[TypeParserOptions]
+        self, name: str, properties: JSONSchema, **kwargs: Unpack[TypeParserOptions]
     ) -> tuple[T, dict]:
         """
         Abstract method to convert properties to a type and its fields properties.
@@ -32,7 +32,7 @@ class GenericTypeParser(ABC, Generic[T]):
         """
 
     def from_properties(
-        self, name: str, properties: dict[str, Any], **kwargs: Unpack[TypeParserOptions]
+        self, name: str, properties: JSONSchema, **kwargs: Unpack[TypeParserOptions]
     ) -> tuple[T, dict]:
         """
         Converts properties to a type and its fields properties.
@@ -54,7 +54,7 @@ class GenericTypeParser(ABC, Generic[T]):
 
     @classmethod
     def type_from_properties(
-        cls, name: str, properties: dict[str, Any], **kwargs: Unpack[TypeParserOptions]
+        cls, name: str, properties: JSONSchema, **kwargs: Unpack[TypeParserOptions]
     ) -> tuple[type, dict]:
         """
         Factory method to fetch the appropriate type parser based on properties
@@ -69,14 +69,14 @@ class GenericTypeParser(ABC, Generic[T]):
         return parser().from_properties(name=name, properties=properties, **kwargs)
 
     @classmethod
-    def _get_impl(cls, properties: dict[str, Any]) -> type[Self]:
+    def _get_impl(cls, properties: JSONSchema) -> type[Self]:
         for subcls in cls.__subclasses__():
             schema_type, schema_value = subcls._get_schema_type()
 
             if schema_type not in properties:
                 continue
 
-            if schema_value is None or schema_value == properties[schema_type]:
+            if schema_value is None or schema_value == properties[schema_type]:  # type: ignore
                 return subcls
 
         raise ValueError("Unknown type")
@@ -108,7 +108,7 @@ class GenericTypeParser(ABC, Generic[T]):
         }
 
     @staticmethod
-    def _validate_default(field_type: type, field_prop: dict) -> bool:
+    def _validate_default(field_type: T, field_prop: dict) -> bool:
         value = field_prop.get("default")
 
         if value is None and field_prop.get("default_factory") is not None:
@@ -118,7 +118,7 @@ class GenericTypeParser(ABC, Generic[T]):
             return True
 
         try:
-            field = Annotated[field_type, Field(**field_prop)]
+            field = Annotated[field_type, Field(**field_prop)]  # type: ignore
             TypeAdapter(field).validate_python(value)
         except Exception as _:
             return False
diff --git a/jambo/parser/allof_type_parser.py b/jambo/parser/allof_type_parser.py
index 3180ae3..2fb62f9 100644
--- a/jambo/parser/allof_type_parser.py
+++ b/jambo/parser/allof_type_parser.py
@@ -1,7 +1,8 @@
 from jambo.parser._type_parser import GenericTypeParser
+from jambo.types.json_schema_type import JSONSchema
 from jambo.types.type_parser_options import TypeParserOptions
 
-from typing_extensions import Any, Unpack
+from typing_extensions import Unpack
 
 
 class AllOfTypeParser(GenericTypeParser):
@@ -10,7 +11,7 @@ class AllOfTypeParser(GenericTypeParser):
     json_schema_type = "allOf"
 
     def from_properties_impl(
-        self, name, properties, **kwargs: Unpack[TypeParserOptions]
+        self, name: str, properties: JSONSchema, **kwargs: Unpack[TypeParserOptions]
     ):
         sub_properties = properties.get("allOf", [])
 
@@ -29,12 +30,12 @@ class AllOfTypeParser(GenericTypeParser):
 
     @staticmethod
     def _get_type_parser(
-        sub_properties: list[dict[str, Any]],
+        sub_properties: list[JSONSchema],
     ) -> type[GenericTypeParser]:
         if not sub_properties:
             raise ValueError("Invalid JSON Schema: 'allOf' is empty.")
 
-        parsers = set(
+        parsers: set[type[GenericTypeParser]] = set(
             GenericTypeParser._get_impl(sub_property) for sub_property in sub_properties
         )
         if len(parsers) != 1:
@@ -44,17 +45,19 @@ class AllOfTypeParser(GenericTypeParser):
 
     @staticmethod
     def _rebuild_properties_from_subproperties(
-        sub_properties: list[dict[str, Any]],
-    ) -> dict[str, Any]:
-        properties = {}
+        sub_properties: list[JSONSchema],
+    ) -> JSONSchema:
+        properties: JSONSchema = {}
         for subProperty in sub_properties:
             for name, prop in subProperty.items():
                 if name not in properties:
-                    properties[name] = prop
+                    properties[name] = prop  # type: ignore
                 else:
                     # Merge properties if they exist in both sub-properties
-                    properties[name] = AllOfTypeParser._validate_prop(
-                        name, properties[name], prop
+                    properties[name] = AllOfTypeParser._validate_prop(  # type: ignore
+                        name,
+                        properties[name],  # type: ignore
+                        prop,
                     )
         return properties
 
diff --git a/jambo/parser/enum_type_parser.py b/jambo/parser/enum_type_parser.py
index 42f4d6f..c59a725 100644
--- a/jambo/parser/enum_type_parser.py
+++ b/jambo/parser/enum_type_parser.py
@@ -1,6 +1,6 @@
 from jambo.parser._type_parser import GenericTypeParser
 from jambo.types.json_schema_type import JSONSchemaNativeTypes
-from jambo.types.type_parser_options import TypeParserOptions
+from jambo.types.type_parser_options import JSONSchema, TypeParserOptions
 
 from typing_extensions import Unpack
 
@@ -11,7 +11,7 @@ class EnumTypeParser(GenericTypeParser):
     json_schema_type = "enum"
 
     def from_properties_impl(
-        self, name, properties, **kwargs: Unpack[TypeParserOptions]
+        self, name: str, properties: JSONSchema, **kwargs: Unpack[TypeParserOptions]
     ):
         if "enum" not in properties:
             raise ValueError(f"Enum type {name} must have 'enum' property defined.")
@@ -27,7 +27,7 @@ class EnumTypeParser(GenericTypeParser):
             )
 
         # Create a new Enum type dynamically
-        enum_type = Enum(name, {str(value).upper(): value for value in enum_values})
+        enum_type = Enum(name, {str(value).upper(): value for value in enum_values})  # type: ignore
         parsed_properties = self.mappings_properties_builder(properties, **kwargs)
 
         if "default" in parsed_properties and parsed_properties["default"] is not None:
diff --git a/jambo/parser/object_type_parser.py b/jambo/parser/object_type_parser.py
index 0f0ab7e..6cb60e7 100644
--- a/jambo/parser/object_type_parser.py
+++ b/jambo/parser/object_type_parser.py
@@ -1,8 +1,10 @@
 from jambo.parser._type_parser import GenericTypeParser
+from jambo.types.json_schema_type import JSONSchema
 from jambo.types.type_parser_options import TypeParserOptions
 
 from pydantic import BaseModel, ConfigDict, Field, create_model
-from typing_extensions import Any, Unpack
+from pydantic.fields import FieldInfo
+from typing_extensions import Unpack
 
 
 class ObjectTypeParser(GenericTypeParser):
@@ -11,7 +13,7 @@ class ObjectTypeParser(GenericTypeParser):
     json_schema_type = "type:object"
 
     def from_properties_impl(
-        self, name: str, properties: dict[str, Any], **kwargs: Unpack[TypeParserOptions]
+        self, name: str, properties: JSONSchema, **kwargs: Unpack[TypeParserOptions]
     ) -> tuple[type[BaseModel], dict]:
         type_parsing = self.to_model(
             name,
@@ -32,29 +34,29 @@ class ObjectTypeParser(GenericTypeParser):
     def to_model(
         cls,
         name: str,
-        schema: dict[str, Any],
+        properties: dict[str, JSONSchema],
         required_keys: list[str],
         **kwargs: Unpack[TypeParserOptions],
     ) -> type[BaseModel]:
         """
         Converts JSON Schema object properties to a Pydantic model.
         :param name: The name of the model.
-        :param schema: The properties of the JSON Schema object.
+        :param properties: The properties of the JSON Schema object.
         :param required_keys: List of required keys in the schema.
         :return: A Pydantic model class.
         """
         model_config = ConfigDict(validate_assignment=True)
-        fields = cls._parse_properties(schema, required_keys, **kwargs)
+        fields = cls._parse_properties(properties, required_keys, **kwargs)
 
-        return create_model(name, __config__=model_config, **fields)
+        return create_model(name, __config__=model_config, **fields)  # type: ignore
 
     @classmethod
     def _parse_properties(
         cls,
-        properties: dict[str, Any],
+        properties: dict[str, JSONSchema],
         required_keys: list[str],
         **kwargs: Unpack[TypeParserOptions],
-    ) -> dict[str, tuple[type, Field]]:
+    ) -> dict[str, tuple[type, FieldInfo]]:
         required_keys = required_keys or []
 
         fields = {}
@@ -63,7 +65,9 @@ class ObjectTypeParser(GenericTypeParser):
             sub_property["required"] = name in required_keys
 
             parsed_type, parsed_properties = GenericTypeParser.type_from_properties(
-                name, prop, **sub_property
+                name,
+                prop,
+                **sub_property,  # type: ignore
             )
             fields[name] = (parsed_type, Field(**parsed_properties))
 
diff --git a/jambo/parser/oneof_type_parser.py b/jambo/parser/oneof_type_parser.py
index 707d277..317ce61 100644
--- a/jambo/parser/oneof_type_parser.py
+++ b/jambo/parser/oneof_type_parser.py
@@ -5,6 +5,9 @@ from pydantic import BaseModel, BeforeValidator, Field, TypeAdapter, ValidationE
 from typing_extensions import Annotated, Any, Union, Unpack, get_args
 
 
+Annotation = Annotated[Any, ...]
+
+
 class OneOfTypeParser(GenericTypeParser):
     mapped_type = Union
 
@@ -49,8 +52,8 @@ class OneOfTypeParser(GenericTypeParser):
 
     @staticmethod
     def _build_type_one_of_with_discriminator(
-        subfield_types: list[Annotated], discriminator_prop: dict
-    ) -> Annotated:
+        subfield_types: list[Annotation], discriminator_prop: dict
+    ) -> Annotation:
         """
         Build a type with a discriminator.
         """
@@ -74,7 +77,7 @@ class OneOfTypeParser(GenericTypeParser):
         return Annotated[Union[(*subfield_types,)], Field(discriminator=property_name)]
 
     @staticmethod
-    def _build_type_one_of_with_func(subfield_types: list[Annotated]) -> Annotated:
+    def _build_type_one_of_with_func(subfield_types: list[Annotation]) -> Annotation:
         """
         Build a type with a validation function for the oneOf constraint.
         """
diff --git a/jambo/parser/ref_type_parser.py b/jambo/parser/ref_type_parser.py
index 57abeac..7aa435d 100644
--- a/jambo/parser/ref_type_parser.py
+++ b/jambo/parser/ref_type_parser.py
@@ -1,10 +1,11 @@
 from jambo.parser import GenericTypeParser
+from jambo.types.json_schema_type import JSONSchema
 from jambo.types.type_parser_options import TypeParserOptions
 
-from typing_extensions import Any, ForwardRef, Literal, TypeVar, Union, Unpack
+from typing_extensions import ForwardRef, Literal, Union, Unpack
 
 
-RefType = TypeVar("RefType", bound=Union[type, ForwardRef])
+RefType = Union[type, ForwardRef]
 
 RefStrategy = Literal["forward_ref", "def_ref"]
 
@@ -13,7 +14,7 @@ class RefTypeParser(GenericTypeParser):
     json_schema_type = "$ref"
 
     def from_properties_impl(
-        self, name: str, properties: dict[str, Any], **kwargs: Unpack[TypeParserOptions]
+        self, name: str, properties: JSONSchema, **kwargs: Unpack[TypeParserOptions]
     ) -> tuple[RefType, dict]:
         if "$ref" not in properties:
             raise ValueError(f"RefTypeParser: Missing $ref in properties for {name}")
@@ -41,19 +42,19 @@ class RefTypeParser(GenericTypeParser):
             # If the reference is either processing or already cached
             return ref_state, mapped_properties
 
-        ref_cache[ref_name] = self._parse_from_strategy(
-            ref_strategy, ref_name, ref_property, **kwargs
-        )
+        ref = self._parse_from_strategy(ref_strategy, ref_name, ref_property, **kwargs)
+        ref_cache[ref_name] = ref
 
-        return ref_cache[ref_name], mapped_properties
+        return ref, mapped_properties
 
     def _parse_from_strategy(
         self,
         ref_strategy: RefStrategy,
         ref_name: str,
-        ref_property: dict[str, Any],
+        ref_property: JSONSchema,
         **kwargs: Unpack[TypeParserOptions],
-    ):
+    ) -> RefType:
+        mapped_type: RefType
         match ref_strategy:
             case "forward_ref":
                 mapped_type = ForwardRef(ref_name)
@@ -69,7 +70,7 @@ class RefTypeParser(GenericTypeParser):
         return mapped_type
 
     def _get_ref_from_cache(
-        self, ref_name: str, ref_cache: dict[str, type]
+        self, ref_name: str, ref_cache: dict[str, ForwardRef | type | None]
     ) -> RefType | type | None:
         try:
             ref_state = ref_cache[ref_name]
@@ -84,10 +85,12 @@ class RefTypeParser(GenericTypeParser):
             # If the reference is not in the cache, we will set it to None
             ref_cache[ref_name] = None
 
+        return None
+
     def _examine_ref_strategy(
-        self, name: str, properties: dict[str, Any], **kwargs: Unpack[TypeParserOptions]
-    ) -> tuple[RefStrategy, str, dict] | None:
-        if properties["$ref"] == "#":
+        self, name: str, properties: JSONSchema, **kwargs: Unpack[TypeParserOptions]
+    ) -> tuple[RefStrategy, str, JSONSchema]:
+        if properties.get("$ref") == "#":
             ref_name = kwargs["context"].get("title")
             if ref_name is None:
                 raise ValueError(
@@ -95,7 +98,7 @@ class RefTypeParser(GenericTypeParser):
                 )
             return "forward_ref", ref_name, {}
 
-        if properties["$ref"].startswith("#/$defs/"):
+        if properties.get("$ref", "").startswith("#/$defs/"):
             target_name, target_property = self._extract_target_ref(
                 name, properties, **kwargs
             )
@@ -106,8 +109,8 @@ class RefTypeParser(GenericTypeParser):
         )
 
     def _extract_target_ref(
-        self, name: str, properties: dict[str, Any], **kwargs: Unpack[TypeParserOptions]
-    ) -> tuple[str, dict]:
+        self, name: str, properties: JSONSchema, **kwargs: Unpack[TypeParserOptions]
+    ) -> tuple[str, JSONSchema]:
         target_name = None
         target_property = kwargs["context"]
         for prop_name in properties["$ref"].split("/")[1:]:
@@ -117,9 +120,9 @@ class RefTypeParser(GenericTypeParser):
                     " properties for $ref {properties['$ref']}"
                 )
             target_name = prop_name
-            target_property = target_property[prop_name]
+            target_property = target_property[prop_name]  # type: ignore
 
-        if target_name is None or target_property is None:
+        if not isinstance(target_name, str) or target_property is None:
             raise ValueError(f"RefTypeParser: Invalid $ref {properties['$ref']}")
 
         return target_name, target_property
diff --git a/jambo/schema_converter.py b/jambo/schema_converter.py
index 6f9020e..1624940 100644
--- a/jambo/schema_converter.py
+++ b/jambo/schema_converter.py
@@ -25,7 +25,7 @@ class SchemaConverter:
 
         try:
             validator = validator_for(schema)
-            validator.check_schema(schema)
+            validator.check_schema(schema)  # type: ignore
         except SchemaError as e:
             raise ValueError(f"Invalid JSON Schema: {e}")
 
@@ -38,10 +38,11 @@ class SchemaConverter:
             case "object":
                 return ObjectTypeParser.to_model(
                     schema["title"],
-                    schema["properties"],
+                    schema.get("properties", {}),
                     schema.get("required", []),
                     context=schema,
                     ref_cache=dict(),
+                    required=True,
                 )
 
             case "$ref":
@@ -50,13 +51,14 @@ class SchemaConverter:
                     schema,
                     context=schema,
                     ref_cache=dict(),
+                    required=True,
                 )
                 return parsed_model
             case _:
                 raise TypeError(f"Unsupported schema type: {schema_type}")
 
     @staticmethod
-    def _get_schema_type(schema: JSONSchema) -> str:
+    def _get_schema_type(schema: JSONSchema) -> str | None:
         """
         Returns the type of the schema.
         :param schema: The JSON Schema to check.
@@ -65,4 +67,4 @@ class SchemaConverter:
         if "$ref" in schema:
             return "$ref"
 
-        return schema.get("type", "undefined")
+        return schema.get("type")
diff --git a/jambo/types/json_schema_type.py b/jambo/types/json_schema_type.py
index d99d791..954db75 100644
--- a/jambo/types/json_schema_type.py
+++ b/jambo/types/json_schema_type.py
@@ -1,93 +1,80 @@
-from typing_extensions import Dict, List, Literal, TypedDict, Union
+from __future__ import annotations
+
+from typing_extensions import (
+    Dict,
+    List,
+    Literal,
+    TypedDict,
+    Union,
+)
 
 from types import NoneType
 
 
+# Primitive JSON types
 JSONSchemaType = Literal[
     "string", "number", "integer", "boolean", "object", "array", "null"
 ]
 
-
 JSONSchemaNativeTypes: tuple[type, ...] = (
     str,
-    int,
     float,
+    int,
     bool,
     list,
     set,
     NoneType,
 )
 
-
 JSONType = Union[str, int, float, bool, None, Dict[str, "JSONType"], List["JSONType"]]
 
-
-class JSONSchema(TypedDict, total=False):
-    # Basic metadata
-    title: str
-    description: str
-    default: JSONType
-    examples: List[JSONType]
-
-    # Type definitions
-    type: Union[JSONSchemaType, List[JSONSchemaType]]
-
-    # Object-specific keywords
-    properties: Dict[str, "JSONSchema"]
-    required: List[str]
-    additionalProperties: Union[bool, "JSONSchema"]
-    minProperties: int
-    maxProperties: int
-    patternProperties: Dict[str, "JSONSchema"]
-    dependencies: Dict[str, Union[List[str], "JSONSchema"]]
-
-    # Array-specific keywords
-    items: Union["JSONSchema", List["JSONSchema"]]
-    additionalItems: Union[bool, "JSONSchema"]
-    minItems: int
-    maxItems: int
-    uniqueItems: bool
-
-    # String-specific keywords
-    minLength: int
-    maxLength: int
-    pattern: str
-    format: str
-
-    # Number-specific keywords
-    minimum: float
-    maximum: float
-    exclusiveMinimum: float
-    exclusiveMaximum: float
-    multipleOf: float
-
-    # Enum and const
-    enum: List[JSONType]
-    const: JSONType
-
-    # Conditionals
-    if_: "JSONSchema"  # 'if' is a reserved word in Python
-    then: "JSONSchema"
-    else_: "JSONSchema"  # 'else' is also a reserved word
-
-    # Combination keywords
-    allOf: List["JSONSchema"]
-    anyOf: List["JSONSchema"]
-    oneOf: List["JSONSchema"]
-    not_: "JSONSchema"  # 'not' is a reserved word
-
-
-# Fix forward references
-JSONSchema.__annotations__["properties"] = Dict[str, JSONSchema]
-JSONSchema.__annotations__["items"] = Union[JSONSchema, List[JSONSchema]]
-JSONSchema.__annotations__["additionalItems"] = Union[bool, JSONSchema]
-JSONSchema.__annotations__["additionalProperties"] = Union[bool, JSONSchema]
-JSONSchema.__annotations__["patternProperties"] = Dict[str, JSONSchema]
-JSONSchema.__annotations__["dependencies"] = Dict[str, Union[List[str], JSONSchema]]
-JSONSchema.__annotations__["if_"] = JSONSchema
-JSONSchema.__annotations__["then"] = JSONSchema
-JSONSchema.__annotations__["else_"] = JSONSchema
-JSONSchema.__annotations__["allOf"] = List[JSONSchema]
-JSONSchema.__annotations__["anyOf"] = List[JSONSchema]
-JSONSchema.__annotations__["oneOf"] = List[JSONSchema]
-JSONSchema.__annotations__["not_"] = JSONSchema
+# Dynamically define TypedDict with JSON Schema keywords
+JSONSchema = TypedDict(
+    "JSONSchema",
+    {
+        "$id": str,
+        "$schema": str,
+        "$ref": str,
+        "$anchor": str,
+        "$comment": str,
+        "$defs": Dict[str, "JSONSchema"],
+        "title": str,
+        "description": str,
+        "default": JSONType,
+        "examples": List[JSONType],
+        "type": JSONSchemaType,
+        "enum": List[JSONType],
+        "const": JSONType,
+        "properties": Dict[str, "JSONSchema"],
+        "patternProperties": Dict[str, "JSONSchema"],
+        "additionalProperties": Union[bool, "JSONSchema"],
+        "required": List[str],
+        "minProperties": int,
+        "maxProperties": int,
+        "dependencies": Dict[str, Union[List[str], "JSONSchema"]],
+        "items": Union["JSONSchema", List["JSONSchema"]],
+        "prefixItems": List["JSONSchema"],
+        "additionalItems": Union[bool, "JSONSchema"],
+        "contains": "JSONSchema",
+        "minItems": int,
+        "maxItems": int,
+        "uniqueItems": bool,
+        "minLength": int,
+        "maxLength": int,
+        "pattern": str,
+        "format": str,
+        "minimum": float,
+        "maximum": float,
+        "exclusiveMinimum": Union[bool, float],
+        "exclusiveMaximum": Union[bool, float],
+        "multipleOf": float,
+        "if": "JSONSchema",
+        "then": "JSONSchema",
+        "else": "JSONSchema",
+        "allOf": List["JSONSchema"],
+        "anyOf": List["JSONSchema"],
+        "oneOf": List["JSONSchema"],
+        "not": "JSONSchema",
+    },
+    total=False,  # all fields optional
+)
diff --git a/jambo/types/type_parser_options.py b/jambo/types/type_parser_options.py
index 4f7d8e0..baf518b 100644
--- a/jambo/types/type_parser_options.py
+++ b/jambo/types/type_parser_options.py
@@ -1,9 +1,9 @@
 from jambo.types.json_schema_type import JSONSchema
 
-from typing_extensions import TypedDict
+from typing_extensions import ForwardRef, TypedDict
 
 
 class TypeParserOptions(TypedDict):
     required: bool
     context: JSONSchema
-    ref_cache: dict[str, type]
+    ref_cache: dict[str, ForwardRef | type | None]
diff --git a/pyproject.toml b/pyproject.toml
index 9aab917..34e1fee 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -31,12 +31,14 @@ dependencies = [
 [dependency-groups]
 dev = [
     "coverage>=7.8.0",
+    "mypy>=1.18.1",
     "poethepoet>=0.33.1",
     "pre-commit>=4.2.0",
     "ruff>=0.11.4",
     "sphinx>=8.1.3",
     "sphinx-autobuild>=2024.10.3",
     "sphinx-rtd-theme>=3.0.2",
+    "types-jsonschema>=4.25.1.20250822",
 ]
 
 
@@ -50,7 +52,8 @@ repository = "https://github.com/HideyoshiNakazone/jambo.git"
 create-hooks        = "bash .githooks/set-hooks.sh"
 tests               = "python -m coverage run -m unittest discover -v"
 tests-report        = "python -m coverage xml"
-serve-docs         = "sphinx-autobuild docs/source docs/build"
+type-check          = "mypy jambo"
+serve-docs          = "sphinx-autobuild docs/source docs/build"
 
 # Build System
 [tool.hatch.version]
diff --git a/tests/test_schema_converter.py b/tests/test_schema_converter.py
index cdd294d..6f831f2 100644
--- a/tests/test_schema_converter.py
+++ b/tests/test_schema_converter.py
@@ -26,6 +26,20 @@ class TestSchemaConverter(TestCase):
         with self.assertRaises(ValueError):
             SchemaConverter.build(schema)
 
+    def test_invalid_schema_type(self):
+        schema = {
+            "title": 1,
+            "description": "A person",
+            "type": 1,
+            "properties": {
+                "name": {"type": "string"},
+                "age": {"type": "integer"},
+            },
+        }
+
+        with self.assertRaises(ValueError):
+            SchemaConverter.build(schema)
+
     def test_build_expects_title(self):
         schema = {
             "description": "A person",
diff --git a/uv.lock b/uv.lock
index 541d6f5..da0c1b5 100644
--- a/uv.lock
+++ b/uv.lock
@@ -326,6 +326,7 @@ dependencies = [
 [package.dev-dependencies]
 dev = [
     { name = "coverage" },
+    { name = "mypy" },
     { name = "poethepoet" },
     { name = "pre-commit" },
     { name = "ruff" },
@@ -333,6 +334,7 @@ dev = [
     { name = "sphinx", version = "8.2.3", source = { registry = "https://pypi.org/simple" }, marker = "python_full_version >= '3.11'" },
     { name = "sphinx-autobuild" },
     { name = "sphinx-rtd-theme" },
+    { name = "types-jsonschema" },
 ]
 
 [package.metadata]
@@ -345,12 +347,14 @@ requires-dist = [
 [package.metadata.requires-dev]
 dev = [
     { name = "coverage", specifier = ">=7.8.0" },
+    { name = "mypy", specifier = ">=1.18.1" },
     { name = "poethepoet", specifier = ">=0.33.1" },
     { name = "pre-commit", specifier = ">=4.2.0" },
     { name = "ruff", specifier = ">=0.11.4" },
     { name = "sphinx", specifier = ">=8.1.3" },
     { name = "sphinx-autobuild", specifier = ">=2024.10.3" },
     { name = "sphinx-rtd-theme", specifier = ">=3.0.2" },
+    { name = "types-jsonschema", specifier = ">=4.25.1.20250822" },
 ]
 
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 ]
 
+[[package]]
+name = "mypy"
+version = "1.18.1"
+source = { registry = "https://pypi.org/simple" }
+dependencies = [
+    { name = "mypy-extensions" },
+    { name = "pathspec" },
+    { name = "tomli", marker = "python_full_version < '3.11'" },
+    { name = "typing-extensions" },
+]
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