diff --git a/src/inspect_ai/model/_providers/anthropic.py b/src/inspect_ai/model/_providers/anthropic.py
index 18508e95c..407552aa0 100644
--- a/src/inspect_ai/model/_providers/anthropic.py
+++ b/src/inspect_ai/model/_providers/anthropic.py
@@ -288,6 +288,13 @@ async def message_param(message: ChatMessage) -> MessageParam:
             content: str | list[TextBlockParam | ImageBlockParam] = (
                 message.error.message
             )
+            # anthropic requires that content be populated when
+            # is_error is true (throws bad_request_error when not)
+            # so make sure this precondition is met
+            if not content:
+                content = message.text
+            if not content:
+                content = "error"
         elif isinstance(message.content, str):
             content = [TextBlockParam(type="text", text=message.content)]
         else:
diff --git a/src/inspect_ai/tool/_tools/_execute.py b/src/inspect_ai/tool/_tools/_execute.py
index 86d08d6d7..89ae1709f 100644
--- a/src/inspect_ai/tool/_tools/_execute.py
+++ b/src/inspect_ai/tool/_tools/_execute.py
@@ -30,7 +30,9 @@ async def execute(cmd: str) -> str:
         if result.success:
             return result.stdout
         else:
-            raise ToolError(result.stderr)
+            raise ToolError(
+                result.stderr if result.stderr else "error executing command"
+            )
 
     return execute
 
@@ -62,6 +64,6 @@ async def execute(code: str) -> str:
         if result.success:
             return result.stdout
         else:
-            raise ToolError(result.stderr)
+            raise ToolError(result.stderr if result.stderr else "error executing code")
 
     return execute