diff --git a/decart/models.py b/decart/models.py
index 2e59c47..7eca043 100644
--- a/decart/models.py
+++ b/decart/models.py
@@ -32,21 +32,29 @@ class ModelDefinition(DecartBaseModel):
 
 
 class TextToVideoInput(BaseModel):
-    prompt: str = Field(..., min_length=1)
+    prompt: str = Field(..., min_length=1, max_length=1000)
     seed: Optional[int] = None
     resolution: Optional[str] = None
     orientation: Optional[str] = None
 
 
 class ImageToVideoInput(DecartBaseModel):
-    prompt: str = Field(..., min_length=1)
+    prompt: str = Field(
+        ...,
+        min_length=1,
+        max_length=1000,
+    )
     data: FileInput
     seed: Optional[int] = None
     resolution: Optional[str] = None
 
 
 class VideoToVideoInput(DecartBaseModel):
-    prompt: str = Field(..., min_length=1)
+    prompt: str = Field(
+        ...,
+        min_length=1,
+        max_length=1000,
+    )
     data: FileInput
     seed: Optional[int] = None
     resolution: Optional[str] = None
@@ -55,7 +63,11 @@ class VideoToVideoInput(DecartBaseModel):
 
 
 class FirstLastFrameInput(DecartBaseModel):
-    prompt: str = Field(..., min_length=1)
+    prompt: str = Field(
+        ...,
+        min_length=1,
+        max_length=1000,
+    )
     start: FileInput
     end: FileInput
     seed: Optional[int] = None
@@ -70,14 +82,22 @@ class ImageToMotionVideoInput(DecartBaseModel):
 
 
 class TextToImageInput(BaseModel):
-    prompt: str = Field(..., min_length=1)
+    prompt: str = Field(
+        ...,
+        min_length=1,
+        max_length=1000,
+    )
     seed: Optional[int] = None
     resolution: Optional[str] = None
     orientation: Optional[str] = None
 
 
 class ImageToImageInput(DecartBaseModel):
-    prompt: str = Field(..., min_length=1)
+    prompt: str = Field(
+        ...,
+        min_length=1,
+        max_length=1000,
+    )
     data: FileInput
     seed: Optional[int] = None
     resolution: Optional[str] = None
diff --git a/tests/test_process.py b/tests/test_process.py
index fcd6e92..d717db9 100644
--- a/tests/test_process.py
+++ b/tests/test_process.py
@@ -87,6 +87,22 @@ async def test_process_video_to_video() -> None:
         assert result == b"fake video data"
 
 
+@pytest.mark.asyncio
+async def test_process_max_prompt_length() -> None:
+    client = DecartClient(api_key="test-key")
+    prompt = "a" * 1001
+    with pytest.raises(DecartSDKError) as exception:
+        await client.process(
+            {
+                "model": models.image("lucy-pro-t2i"),
+                "prompt": prompt,
+            }
+        )
+    assert "Invalid inputs for lucy-pro-t2i: 1 validation error for TextToImageInput" in str(
+        exception
+    )
+
+
 @pytest.mark.asyncio
 async def test_process_image_to_motion_video() -> None:
     client = DecartClient(api_key="test-key")
diff --git a/uv.lock b/uv.lock
index a15cbf3..0b2dadf 100644
--- a/uv.lock
+++ b/uv.lock
@@ -900,7 +900,7 @@ wheels = [
 
 [[package]]
 name = "decart"
-version = "0.0.7"
+version = "0.0.8"
 source = { editable = "." }
 dependencies = [
     { name = "aiofiles" },