diff --git a/letta/server/server.py b/letta/server/server.py
index 39536c66..9c66832e 100644
--- a/letta/server/server.py
+++ b/letta/server/server.py
@@ -1954,8 +1954,6 @@ class SyncServer(Server):
         # Next, attempt to run the tool with the sandbox
         try:
             sandbox_run_result = ToolExecutionSandbox(tool.name, tool_args_dict, user_id, tool_object=tool).run(agent_state=agent_state)
-            if sandbox_run_result is None:
-                raise ValueError(f"Tool with id {tool.id} returned execution with None")
             function_response = str(sandbox_run_result.func_return)
             stdout = [s for s in sandbox_run_result.stdout if s.strip()]
             stderr = [s for s in sandbox_run_result.stderr if s.strip()]
diff --git a/letta/services/tool_execution_sandbox.py b/letta/services/tool_execution_sandbox.py
index 9adcff0b..3aac64b5 100644
--- a/letta/services/tool_execution_sandbox.py
+++ b/letta/services/tool_execution_sandbox.py
@@ -62,7 +62,7 @@ class ToolExecutionSandbox:
         self.sandbox_config_manager = SandboxConfigManager(tool_settings)
         self.force_recreate = force_recreate
 
-    def run(self, agent_state: Optional[AgentState] = None) -> Optional[SandboxRunResult]:
+    def run(self, agent_state: Optional[AgentState] = None) -> SandboxRunResult:
         """
         Run the tool in a sandbox environment.
 
@@ -101,7 +101,7 @@ class ToolExecutionSandbox:
             os.environ.clear()
             os.environ.update(original_env)  # Restore original environment variables
 
-    def run_local_dir_sandbox(self, agent_state: AgentState) -> Optional[SandboxRunResult]:
+    def run_local_dir_sandbox(self, agent_state: AgentState) -> SandboxRunResult:
         sbx_config = self.sandbox_config_manager.get_or_create_default_sandbox_config(sandbox_type=SandboxType.LOCAL, actor=self.user)
         local_configs = sbx_config.get_local_config()
 
@@ -266,7 +266,7 @@ class ToolExecutionSandbox:
 
     # e2b sandbox specific functions
 
-    def run_e2b_sandbox(self, agent_state: AgentState) -> Optional[SandboxRunResult]:
+    def run_e2b_sandbox(self, agent_state: AgentState) -> SandboxRunResult:
         sbx_config = self.sandbox_config_manager.get_or_create_default_sandbox_config(sandbox_type=SandboxType.E2B, actor=self.user)
         sbx = self.get_running_e2b_sandbox_with_same_state(sbx_config)
         if not sbx or self.force_recreate:
@@ -286,7 +286,7 @@ class ToolExecutionSandbox:
             execution.logs.stderr.append(execution.error.traceback) 
             execution.logs.stderr.append(f"{execution.error.name}: {execution.error.value}") 
         elif len(execution.results) == 0:
-            return None
+            raise ValueError(f"Tool {self.tool_name} returned execution with None")
         else:
             func_return, agent_state = self.parse_best_effort(execution.results[0].text)
         return SandboxRunResult(