diff --git a/python/packages/core/agent_framework/observability.py b/python/packages/core/agent_framework/observability.py
index 1654799d87..48bf1314f8 100644
--- a/python/packages/core/agent_framework/observability.py
+++ b/python/packages/core/agent_framework/observability.py
@@ -2093,6 +2093,15 @@ def _get_instructions_from_options(options: Any) -> str | list[str] | None:
     return None
 
 
+def _serialize_tool_definitions(tools: Any) -> list[str] | None:
+    from agent_framework._tools import _tools_to_dict
+
+    tools_dict = _tools_to_dict(tools)
+    if not tools_dict:
+        return None
+    return [json.dumps(tool_def, ensure_ascii=False) for tool_def in tools_dict]
+
+
 # Mapping configuration for extracting span attributes
 # Each entry: source_keys -> (otel_attribute_key, transform_func, check_options_first, default_value)
 # - source_keys: single key or list of keys to check (first non-None value wins)
@@ -2128,11 +2137,7 @@ def _get_instructions_from_options(options: Any) -> str | list[str] | None:
     # Tools with validation - returns None if no valid tools
     "tools": (
         OtelAttr.TOOL_DEFINITIONS,
-        lambda tools: (
-            json.dumps(tools_dict, ensure_ascii=False)
-            if (tools_dict := __import__("agent_framework._tools", fromlist=["_tools_to_dict"])._tools_to_dict(tools))
-            else None
-        ),
+        _serialize_tool_definitions,
         True,
         None,
     ),
diff --git a/python/packages/core/tests/core/test_observability.py b/python/packages/core/tests/core/test_observability.py
index 94d4ee3bad..8617fa86ec 100644
--- a/python/packages/core/tests/core/test_observability.py
+++ b/python/packages/core/tests/core/test_observability.py
@@ -1,5 +1,6 @@
 # Copyright (c) Microsoft. All rights reserved.
 
+import json
 import logging
 from collections.abc import AsyncIterable, Awaitable, MutableSequence, Sequence
 from typing import Any
@@ -2895,6 +2896,22 @@ def test_get_span_attributes_with_agent_info():
     assert attrs[OtelAttr.AGENT_DESCRIPTION] == "A test agent"
 
 
+def test_get_span_attributes_serializes_tool_definitions_individually():
+    from agent_framework.observability import OtelAttr, _get_span_attributes
+
+    @tool
+    def lookup_weather(city: str) -> str:
+        return f"sunny in {city}"
+
+    attrs = _get_span_attributes(tools=[lookup_weather])
+    definitions = attrs[OtelAttr.TOOL_DEFINITIONS]
+
+    assert isinstance(definitions, list)
+    assert len(definitions) == 1
+    definition = json.loads(definitions[0])
+    assert definition["function"]["name"] == "lookup_weather"
+
+
 # region Test _capture_response