Harden M7.6/7.7: recursive restriction accumulation, MCP server enforcement, fast-fail authorization

tests/test_tool.py

@@ -609,6 +609,35 @@ class TestAgentContext:
         assert "skills" not in d
         assert "profile" not in d
 
+    def test_toolstep_tools_roundtrip(self):
+        step = ToolStep(
+            tool="my-tool", output_var="out", tools=["safe-*", "official/lint"]
+        )
+        assert ToolStep.from_dict(step.to_dict()).tools == [
+            "safe-*", "official/lint"
+        ]
+
+    def test_toolstep_empty_tools_roundtrip(self):
+        step = ToolStep(tool="my-tool", output_var="out", tools=[])
+        serialized = step.to_dict()
+        assert serialized["tools"] == []
+        assert ToolStep.from_dict(serialized).tools == []
+
+    @pytest.mark.parametrize(
+        "data",
+        [
+            {"skills": "python"},
+            {"skills": ["*", "python"]},
+            {"skills": ["Python"]},
+            {"tools": "safe-tool"},
+            {"tools": [""]},
+            {"profile": ""},
+        ],
+    )
+    def test_toolstep_rejects_invalid_agent_context(self, data):
+        with pytest.raises(ValueError):
+            ToolStep(tool="my-tool", output_var="out", **data)
+
     def test_promptstep_skills_roundtrip(self):
         step = PromptStep(
             prompt="Test", provider="claude", output_var="out",