diff --git a/nanobot/agent/tools/base.py b/nanobot/agent/tools/base.py
index 5e19e5c40..9e63620dd 100644
--- a/nanobot/agent/tools/base.py
+++ b/nanobot/agent/tools/base.py
@@ -2,6 +2,7 @@
 
 from abc import ABC, abstractmethod
 from collections.abc import Callable
+from copy import deepcopy
 from typing import Any, TypeVar
 
 _ToolT = TypeVar("_ToolT", bound="Tool")
@@ -246,7 +247,7 @@ def tool_parameters(schema: dict[str, Any]) -> Callable[[type[_ToolT]], type[_To
     """Class decorator: attach JSON Schema and inject a concrete ``parameters`` property.
 
     Use on ``Tool`` subclasses instead of writing ``@property def parameters``. The
-    schema is stored on the class (shallow-copied) as ``_tool_parameters_schema``.
+    schema is stored on the class and returned as a fresh copy on each access.
 
     Example::
 
@@ -260,13 +261,13 @@ def tool_parameters(schema: dict[str, Any]) -> Callable[[type[_ToolT]], type[_To
     """
 
     def decorator(cls: type[_ToolT]) -> type[_ToolT]:
-        frozen = dict(schema)
+        frozen = deepcopy(schema)
 
         @property
         def parameters(self: Any) -> dict[str, Any]:
-            return frozen
+            return deepcopy(frozen)
 
-        cls._tool_parameters_schema = frozen
+        cls._tool_parameters_schema = deepcopy(frozen)
         cls.parameters = parameters  # type: ignore[assignment]
 
         abstract = getattr(cls, "__abstractmethods__", None)
diff --git a/tests/tools/test_tool_validation.py b/tests/tools/test_tool_validation.py
index b1d56a439..e56f93185 100644
--- a/tests/tools/test_tool_validation.py
+++ b/tests/tools/test_tool_validation.py
@@ -6,6 +6,7 @@ from nanobot.agent.tools import (
     ObjectSchema,
     Schema,
     StringSchema,
+    tool_parameters,
     tool_parameters_schema,
 )
 from nanobot.agent.tools.base import Tool
@@ -49,6 +50,26 @@ class SampleTool(Tool):
         return "ok"
 
 
+@tool_parameters(
+    tool_parameters_schema(
+        query=StringSchema(min_length=2),
+        count=IntegerSchema(2, minimum=1, maximum=10),
+        required=["query", "count"],
+    )
+)
+class DecoratedSampleTool(Tool):
+    @property
+    def name(self) -> str:
+        return "decorated_sample"
+
+    @property
+    def description(self) -> str:
+        return "decorated sample tool"
+
+    async def execute(self, **kwargs: Any) -> str:
+        return f"ok:{kwargs['count']}"
+
+
 def test_schema_validate_value_matches_tool_validate_params() -> None:
     """ObjectSchema.validate_value 与 validate_json_schema_value、Tool.validate_params 一致。"""
     root = tool_parameters_schema(
@@ -101,6 +122,31 @@ def test_schema_classes_equivalent_to_sample_tool_parameters() -> None:
     assert built == SampleTool().parameters
 
 
+def test_tool_parameters_returns_fresh_copy_per_access() -> None:
+    tool = DecoratedSampleTool()
+
+    first = tool.parameters
+    second = tool.parameters
+
+    assert first == second
+    assert first is not second
+    assert first["properties"] is not second["properties"]
+
+    first["properties"]["query"]["minLength"] = 99
+    assert tool.parameters["properties"]["query"]["minLength"] == 2
+
+
+async def test_registry_executes_decorated_tool_end_to_end() -> None:
+    reg = ToolRegistry()
+    reg.register(DecoratedSampleTool())
+
+    ok = await reg.execute("decorated_sample", {"query": "hello", "count": "3"})
+    assert ok == "ok:3"
+
+    err = await reg.execute("decorated_sample", {"query": "h", "count": 3})
+    assert "Invalid parameters" in err
+
+
 def test_validate_params_missing_required() -> None:
     tool = SampleTool()
     errors = tool.validate_params({"query": "hi"})