diff --git a/src/clean_agent_preview.py b/src/clean_agent_preview.py
index 028bda68b..48766cef9 100644
--- a/src/clean_agent_preview.py
+++ b/src/clean_agent_preview.py
@@ -1473,10 +1473,23 @@ def artifact_completion_tool_schemas(offered_schemas, required_artifacts):
         # ``write_file`` deliberately accepts UTF-8 text only. Keeping it in
         # a binary artifact completion round lets a forced writer choice trap
         # the model in an impossible retry loop even when Python is offered.
-        return [
-            copy.deepcopy(schema) for schema in offered_schemas
-            if canonical((schema.get('function') or {}).get('name')) != 'write_file'
-        ]
+        bound = []
+        for source in offered_schemas:
+            if canonical((source.get('function') or {}).get('name')) == 'write_file':
+                continue
+            schema = copy.deepcopy(source)
+            function = schema.get('function') or {}
+            if canonical(function.get('name')) == 'python':
+                properties = (function.get('parameters') or {}).get('properties') or {}
+                code_schema = properties.get('code')
+                if isinstance(code_schema, dict):
+                    code_schema['pattern'] = re.escape(target)
+                    code_schema['description'] = (
+                        'Python code that creates or updates this exact required '
+                        f'binary artifact path: {target}'
+                    )
+            bound.append(schema)
+        return bound
     bound = copy.deepcopy(offered_schemas)
     for schema in bound:
         function = schema.get('function') or {}
diff --git a/tests/test_clean_agent_preview.py b/tests/test_clean_agent_preview.py
index a7c1e9ca6..2dc1b771a 100644
--- a/tests/test_clean_agent_preview.py
+++ b/tests/test_clean_agent_preview.py
@@ -521,7 +521,14 @@ def test_artifact_completion_schema_does_not_bind_directory_or_multiple_outputs(
 def test_required_binary_artifact_forces_python_instead_of_text_writer():
     offered = [
         {'type': 'function', 'function': {'name': 'write_file'}},
-        {'type': 'function', 'function': {'name': 'python'}},
+        {'type': 'function', 'function': {
+            'name': 'python',
+            'parameters': {
+                'type': 'object',
+                'properties': {'code': {'type': 'string'}},
+                'required': ['code'],
+            },
+        }},
     ]
 
     assert required_artifact_completion_tool_choice(
@@ -533,12 +540,14 @@ def test_required_binary_artifact_forces_python_instead_of_text_writer():
     assert required_artifact_completion_tool_choice(
         ('/workspace/output.png',), offered[:1],
     ) is None
-    assert [
-        schema['function']['name']
-        for schema in artifact_completion_tool_schemas(
-            offered, ('/workspace/output.png',),
-        )
-    ] == ['python']
+    binary_bound = artifact_completion_tool_schemas(
+        offered, ('/workspace/output.png',),
+    )
+    assert [schema['function']['name'] for schema in binary_bound] == ['python']
+    code_schema = binary_bound[0]['function']['parameters']['properties']['code']
+    assert re.search(code_schema['pattern'], "open('/workspace/output.png', 'wb')")
+    assert not re.search(code_schema['pattern'], "print('more analysis')")
+    assert '/workspace/output.png' in code_schema['description']
     assert [schema['function']['name'] for schema in offered] == [
         'write_file', 'python',
     ]