diff --git a/openhands-sdk/openhands/sdk/tool/tool.py b/openhands-sdk/openhands/sdk/tool/tool.py
index 0079efb3eb..bd44040948 100644
--- a/openhands-sdk/openhands/sdk/tool/tool.py
+++ b/openhands-sdk/openhands/sdk/tool/tool.py
@@ -1,4 +1,5 @@
 import re
+import threading
 from abc import ABC, abstractmethod
 from collections.abc import Sequence
 from typing import (
@@ -42,6 +43,7 @@
 ObservationT = TypeVar("ObservationT", bound=Observation)
 _action_types_with_risk: dict[type, type] = {}
 _action_types_with_summary: dict[type, type] = {}
+_action_type_lock = threading.Lock()
 
 
 def _camel_to_snake(name: str) -> str:
@@ -477,25 +479,26 @@ def resolve_kind(cls, kind: str) -> type:
 
 
 def create_action_type_with_risk(action_type: type[Schema]) -> type[Schema]:
-    action_type_with_risk = _action_types_with_risk.get(action_type)
-    if action_type_with_risk:
+    with _action_type_lock:
+        action_type_with_risk = _action_types_with_risk.get(action_type)
+        if action_type_with_risk:
+            return action_type_with_risk
+
+        action_type_with_risk = type(
+            f"{action_type.__name__}WithRisk",
+            (action_type,),
+            {
+                "security_risk": Field(
+                    # We do NOT add default value to make it an required field
+                    # default=risk.SecurityRisk.UNKNOWN
+                    description="The LLM's assessment of the safety risk of this action.",  # noqa:E501
+                ),
+                "__annotations__": {"security_risk": risk.SecurityRisk},
+            },
+        )
+        _action_types_with_risk[action_type] = action_type_with_risk
         return action_type_with_risk
 
-    action_type_with_risk = type(
-        f"{action_type.__name__}WithRisk",
-        (action_type,),
-        {
-            "security_risk": Field(
-                # We do NOT add default value to make it an required field
-                # default=risk.SecurityRisk.UNKNOWN
-                description="The LLM's assessment of the safety risk of this action.",
-            ),
-            "__annotations__": {"security_risk": risk.SecurityRisk},
-        },
-    )
-    _action_types_with_risk[action_type] = action_type_with_risk
-    return action_type_with_risk
-
 
 def _create_action_type_with_summary(action_type: type[Schema]) -> type[Schema]:
     """Create a new action type with summary field for LLM to predict.
@@ -509,24 +512,25 @@ def _create_action_type_with_summary(action_type: type[Schema]) -> type[Schema]:
     Returns:
         A new type that includes the summary field
     """
-    action_type_with_summary = _action_types_with_summary.get(action_type)
-    if action_type_with_summary:
-        return action_type_with_summary
-
-    action_type_with_summary = type(
-        f"{action_type.__name__}WithSummary",
-        (action_type,),
-        {
-            "summary": Field(
-                default=None,
-                description=(
-                    "A concise summary (approximately 10 words) describing what "
-                    "this specific action does. Focus on the key operation and target. "
-                    "Example: 'List all Python files in current directory'"
+    with _action_type_lock:
+        action_type_with_summary = _action_types_with_summary.get(action_type)
+        if action_type_with_summary:
+            return action_type_with_summary
+
+        action_type_with_summary = type(
+            f"{action_type.__name__}WithSummary",
+            (action_type,),
+            {
+                "summary": Field(
+                    default=None,
+                    description=(
+                        "A concise summary (approximately 10 words) describing what "
+                        "this specific action does. Focus on the key operation and target. "  # noqa:E501
+                        "Example: 'List all Python files in current directory'"
+                    ),
                 ),
-            ),
-            "__annotations__": {"summary": str | None},
-        },
-    )
-    _action_types_with_summary[action_type] = action_type_with_summary
-    return action_type_with_summary
+                "__annotations__": {"summary": str | None},
+            },
+        )
+        _action_types_with_summary[action_type] = action_type_with_summary
+        return action_type_with_summary
diff --git a/tests/sdk/tool/test_tool.py b/tests/sdk/tool/test_tool.py
index 62ec358bab..cd61727088 100644
--- a/tests/sdk/tool/test_tool.py
+++ b/tests/sdk/tool/test_tool.py
@@ -1,9 +1,26 @@
 """Test Tool class functionality."""
 
+import gc
+import threading
+from abc import ABC
+
 import pytest
-from pydantic import ValidationError
+from pydantic import Field, ValidationError
 
+from openhands.sdk.tool import Action
 from openhands.sdk.tool.spec import Tool
+from openhands.sdk.tool.tool import (
+    _action_types_with_risk,
+    _action_types_with_summary,
+    _create_action_type_with_summary,
+    create_action_type_with_risk,
+)
+from openhands.sdk.utils.models import _get_checked_concrete_subclasses
+
+
+# Must live at module scope (Pydantic rejects <locals> classes).
+class _Bug2199Action(Action, ABC):
+    cmd: str = Field(description="test")
 
 
 def test_tool_minimal():
@@ -177,3 +194,75 @@ def test_tool_repr():
 
     assert "Tool" in repr_str
     assert "TerminalTool" in repr_str
+
+
+def test_issue_2199_1(request):
+    """Reproduce issue #2199: duplicate dynamic Action wrapper classes.
+
+    When subagent threads concurrently call ``create_action_type_with_risk``
+    or ``_create_action_type_with_summary`` on the same input, a TOCTOU race
+    on the module-level cache can create two distinct class objects with the
+    same ``__name__``, causing ``_get_checked_concrete_subclasses(Action)``
+    to raise ``ValueError("Duplicate class definition ...")``.
+
+    Ref: https://github.com/issues/assigned?issue=OpenHands%7Csoftware-agent-sdk%7C2199
+    """
+    """Many threads wrapping the same type must all get the same class object."""
+    saved_risk = dict(_action_types_with_risk)
+
+    def _cleanup():
+        _action_types_with_risk.clear()
+        _action_types_with_risk.update(saved_risk)
+        gc.collect()
+
+    request.addfinalizer(_cleanup)
+
+    results: list[type] = []
+    barrier = threading.Barrier(8)
+
+    def worker():
+        barrier.wait()
+        results.append(create_action_type_with_risk(_Bug2199Action))
+
+    threads = [threading.Thread(target=worker) for _ in range(8)]
+    for t in threads:
+        t.start()
+    for t in threads:
+        t.join()
+
+    assert len(set(id(r) for r in results)) == 1, "All threads must get the same class"
+    _get_checked_concrete_subclasses(Action)
+
+
+def test_issue_2199_2(request):
+    """
+    Same race test for _create_action_type_with_summary.
+    """
+    saved_risk = dict(_action_types_with_risk)
+    saved_summary = dict(_action_types_with_summary)
+
+    def _cleanup():
+        _action_types_with_risk.clear()
+        _action_types_with_risk.update(saved_risk)
+        _action_types_with_summary.clear()
+        _action_types_with_summary.update(saved_summary)
+        gc.collect()
+
+    request.addfinalizer(_cleanup)
+
+    with_risk = create_action_type_with_risk(_Bug2199Action)
+    results: list[type] = []
+    barrier = threading.Barrier(8)
+
+    def worker():
+        barrier.wait()
+        results.append(_create_action_type_with_summary(with_risk))
+
+    threads = [threading.Thread(target=worker) for _ in range(8)]
+    for t in threads:
+        t.start()
+    for t in threads:
+        t.join()
+
+    assert len(set(id(r) for r in results)) == 1, "All threads must get the same class"
+    _get_checked_concrete_subclasses(Action)