diff --git a/backend/danswer/chat/models.py b/backend/danswer/chat/models.py
index d1da783b6f..1828d52508 100644
--- a/backend/danswer/chat/models.py
+++ b/backend/danswer/chat/models.py
@@ -9,6 +9,7 @@ from danswer.search.enums import QueryFlow
 from danswer.search.enums import SearchType
 from danswer.search.models import RetrievalDocs
 from danswer.search.models import SearchResponse
+from danswer.tools.custom.base_tool_types import ToolResultType
 
 
 class LlmDoc(BaseModel):
@@ -130,7 +131,7 @@ class ImageGenerationDisplay(BaseModel):
 
 
 class CustomToolResponse(BaseModel):
-    response: dict
+    response: ToolResultType
     tool_name: str
 
 
diff --git a/backend/danswer/tools/custom/base_tool_types.py b/backend/danswer/tools/custom/base_tool_types.py
new file mode 100644
index 0000000000..7bef9a572c
--- /dev/null
+++ b/backend/danswer/tools/custom/base_tool_types.py
@@ -0,0 +1,2 @@
+# should really be `JSON_ro`, but this causes issues with pydantic
+ToolResultType = dict | list | str | int | float | bool
diff --git a/backend/danswer/tools/custom/custom_tool.py b/backend/danswer/tools/custom/custom_tool.py
index 84f10c3ec0..f7cbf236f2 100644
--- a/backend/danswer/tools/custom/custom_tool.py
+++ b/backend/danswer/tools/custom/custom_tool.py
@@ -11,6 +11,7 @@ from pydantic import BaseModel
 from danswer.dynamic_configs.interface import JSON_ro
 from danswer.llm.answering.models import PreviousMessage
 from danswer.llm.interfaces import LLM
+from danswer.tools.custom.base_tool_types import ToolResultType
 from danswer.tools.custom.custom_tool_prompts import (
     SHOULD_USE_CUSTOM_TOOL_SYSTEM_PROMPT,
 )
@@ -34,7 +35,7 @@ CUSTOM_TOOL_RESPONSE_ID = "custom_tool_response"
 
 class CustomToolCallSummary(BaseModel):
     tool_name: str
-    tool_result: dict
+    tool_result: ToolResultType
 
 
 class CustomTool(Tool):