diff --git a/script/api_protobuf/api_protobuf.py b/script/api_protobuf/api_protobuf.py
index 4295cedeec..fb584bb748 100755
--- a/script/api_protobuf/api_protobuf.py
+++ b/script/api_protobuf/api_protobuf.py
@@ -90,6 +90,10 @@ def force_str(force: bool) -> str:
 class TypeInfo(ABC):
     """Base class for all type information."""
 
+    # Maximum size for fixed-size types (in bytes)
+    # -1 for variable length types
+    maximum_size = -1
+
     def __init__(self, field: descriptor.FieldDescriptorProto) -> None:
         self._field = field
 
@@ -280,6 +284,7 @@ class DoubleType(TypeInfo):
     decode_64bit = "value.as_double()"
     encode_func = "encode_double"
     wire_type = WireType.FIXED64  # Uses wire type 1 according to protobuf spec
+    maximum_size = 8  # 8 bytes for double
 
     def dump(self, name: str) -> str:
         o = f'sprintf(buffer, "%g", {name});\n'
@@ -299,6 +304,7 @@ class FloatType(TypeInfo):
     decode_32bit = "value.as_float()"
     encode_func = "encode_float"
     wire_type = WireType.FIXED32  # Uses wire type 5
+    maximum_size = 4  # 4 bytes for float
 
     def dump(self, name: str) -> str:
         o = f'sprintf(buffer, "%g", {name});\n'
@@ -318,6 +324,7 @@ class Int64Type(TypeInfo):
     decode_varint = "value.as_int64()"
     encode_func = "encode_int64"
     wire_type = WireType.VARINT  # Uses wire type 0
+    maximum_size = 10  # Maximum 10 bytes for varint64
 
     def dump(self, name: str) -> str:
         o = f'sprintf(buffer, "%lld", {name});\n'
@@ -337,6 +344,7 @@ class UInt64Type(TypeInfo):
     decode_varint = "value.as_uint64()"
     encode_func = "encode_uint64"
     wire_type = WireType.VARINT  # Uses wire type 0
+    maximum_size = 10  # Maximum 10 bytes for varint64
 
     def dump(self, name: str) -> str:
         o = f'sprintf(buffer, "%llu", {name});\n'
@@ -356,6 +364,7 @@ class Int32Type(TypeInfo):
     decode_varint = "value.as_int32()"
     encode_func = "encode_int32"
     wire_type = WireType.VARINT  # Uses wire type 0
+    maximum_size = 5  # Maximum 5 bytes for varint32
 
     def dump(self, name: str) -> str:
         o = f'sprintf(buffer, "%" PRId32, {name});\n'
@@ -375,6 +384,7 @@ class Fixed64Type(TypeInfo):
     decode_64bit = "value.as_fixed64()"
     encode_func = "encode_fixed64"
     wire_type = WireType.FIXED64  # Uses wire type 1
+    maximum_size = 8  # 8 bytes for fixed64
 
     def dump(self, name: str) -> str:
         o = f'sprintf(buffer, "%llu", {name});\n'
@@ -394,6 +404,7 @@ class Fixed32Type(TypeInfo):
     decode_32bit = "value.as_fixed32()"
     encode_func = "encode_fixed32"
     wire_type = WireType.FIXED32  # Uses wire type 5
+    maximum_size = 4  # 4 bytes for fixed32
 
     def dump(self, name: str) -> str:
         o = f'sprintf(buffer, "%" PRIu32, {name});\n'
@@ -413,6 +424,7 @@ class BoolType(TypeInfo):
     decode_varint = "value.as_bool()"
     encode_func = "encode_bool"
     wire_type = WireType.VARINT  # Uses wire type 0
+    maximum_size = 1  # 1 byte for bool
 
     def dump(self, name: str) -> str:
         o = f"out.append(YESNO({name}));"
@@ -506,6 +518,7 @@ class UInt32Type(TypeInfo):
     decode_varint = "value.as_uint32()"
     encode_func = "encode_uint32"
     wire_type = WireType.VARINT  # Uses wire type 0
+    maximum_size = 5  # Maximum 5 bytes for varint32
 
     def dump(self, name: str) -> str:
         o = f'sprintf(buffer, "%" PRIu32, {name});\n'
@@ -520,6 +533,8 @@ class UInt32Type(TypeInfo):
 
 @register_type(14)
 class EnumType(TypeInfo):
+    maximum_size = 5  # Maximum 5 bytes for enum (same as uint32)
+
     @property
     def cpp_type(self) -> str:
         return f"enums::{self._field.type_name[1:]}"
@@ -552,6 +567,7 @@ class SFixed32Type(TypeInfo):
     decode_32bit = "value.as_sfixed32()"
     encode_func = "encode_sfixed32"
     wire_type = WireType.FIXED32  # Uses wire type 5
+    maximum_size = 4  # 4 bytes for sfixed32
 
     def dump(self, name: str) -> str:
         o = f'sprintf(buffer, "%" PRId32, {name});\n'
@@ -571,6 +587,7 @@ class SFixed64Type(TypeInfo):
     decode_64bit = "value.as_sfixed64()"
     encode_func = "encode_sfixed64"
     wire_type = WireType.FIXED64  # Uses wire type 1
+    maximum_size = 8  # 8 bytes for sfixed64
 
     def dump(self, name: str) -> str:
         o = f'sprintf(buffer, "%lld", {name});\n'
@@ -590,6 +607,7 @@ class SInt32Type(TypeInfo):
     decode_varint = "value.as_sint32()"
     encode_func = "encode_sint32"
     wire_type = WireType.VARINT  # Uses wire type 0
+    maximum_size = 5  # Maximum 5 bytes for sint32
 
     def dump(self, name: str) -> str:
         o = f'sprintf(buffer, "%" PRId32, {name});\n'
@@ -609,6 +627,7 @@ class SInt64Type(TypeInfo):
     decode_varint = "value.as_sint64()"
     encode_func = "encode_sint64"
     wire_type = WireType.VARINT  # Uses wire type 0
+    maximum_size = 10  # Maximum 10 bytes for sint64
 
     def dump(self, name: str) -> str:
         o = f'sprintf(buffer, "%lld", {name});\n'
@@ -622,6 +641,8 @@ class SInt64Type(TypeInfo):
 
 
 class RepeatedTypeInfo(TypeInfo):
+    maximum_size = -1  # Repeated fields are variable length
+
     def __init__(self, field: descriptor.FieldDescriptorProto) -> None:
         super().__init__(field)
         self._ti: TypeInfo = TYPE_INFO[field.type](field)
@@ -762,30 +783,25 @@ def build_enum_type(desc) -> tuple[str, str]:
     return out, cpp
 
 
-# Maximum sizes for fixed-size protobuf types
-PROTOBUF_TYPE_SIZES = {
-    1: 8,  # DOUBLE
-    2: 4,  # FLOAT
-    3: 10,  # INT64 (max varint size)
-    4: 10,  # UINT64 (max varint size)
-    5: 5,  # INT32 (max varint size)
-    6: 8,  # FIXED64
-    7: 4,  # FIXED32
-    8: 1,  # BOOL
-    # 9: STRING (variable)
-    # 10: GROUP (deprecated)
-    # 11: MESSAGE (variable)
-    # 12: BYTES (variable)
-    13: 5,  # UINT32 (max varint size)
-    14: 5,  # ENUM (same as uint32)
-    15: 4,  # SFIXED32
-    16: 8,  # SFIXED64
-    17: 5,  # SINT32 (max varint size)
-    18: 10,  # SINT64 (max varint size)
-}
+def get_type_sizes():
+    """Dynamically build type size dictionaries from registered types."""
+    # Build PROTOBUF_TYPE_SIZES from TYPE_INFO
+    type_sizes = {}
+    variable_length_types = set()
 
-# Variable length types that cannot have fixed size
-VARIABLE_LENGTH_TYPES = {9, 11, 12}  # STRING, MESSAGE, BYTES
+    for type_id, type_class in TYPE_INFO.items():
+        if hasattr(type_class, "maximum_size"):
+            if type_class.maximum_size == -1:
+                variable_length_types.add(type_id)
+            else:
+                type_sizes[type_id] = type_class.maximum_size
+
+    return type_sizes, variable_length_types
+
+
+# Build the type size mappings once when the module loads
+# This avoids recalculating these dictionaries for every message
+PROTOBUF_TYPE_SIZES, VARIABLE_LENGTH_TYPES = get_type_sizes()
 
 
 def calculate_fixed_message_size(desc: descriptor.DescriptorProto) -> int: