Python: Add MCP server identity to tool execution spans

python/packages/core/agent_framework/_mcp.py

@@ -50,6 +50,8 @@
 )
 from .exceptions import ToolException, ToolExecutionException
 from .observability import (
+    MCP_SERVER_NAME_PROPERTY,
+    MCP_SERVER_URL_PROPERTY,
     OtelAttr,
     create_mcp_client_span,
     set_mcp_span_error,
@@ -808,6 +810,46 @@ def _get_input_model_from_mcp_prompt(prompt: types.Prompt) -> dict[str, Any]:
     return schema
 
 
+def _sanitize_mcp_server_url(url: str | None) -> str | None:
+    """Return an http(s) URL without user info, query string or fragment, else ``None``.
+
+    Query strings and user info commonly carry secrets (API keys, SAS tokens, function keys), so only the
+    scheme, host, port and path are ever copied onto a span.
+    """
+    if not isinstance(url, str) or not url:
+        return None
+    from urllib.parse import urlsplit
+
+    try:
+        parts = urlsplit(url.strip())
+        host = parts.hostname
+        port = parts.port
+    except ValueError:
+        return None
+    if parts.scheme not in {"http", "https"} or not host:
+        return None
+    netloc = f"[{host}]" if ":" in host else host
+    if port is not None:
+        netloc = f"{netloc}:{port}"
+    return f"{parts.scheme}://{netloc}{parts.path}"
+
+
+def _mcp_server_identity_properties(tool: Any) -> dict[str, str]:
+    """Build the ``additional_properties`` entries that identify the MCP server behind an MCP function.
+
+    These feed ``microsoft.tool.server.name`` and ``url.full`` on the ``execute_tool`` span. Values that are
+    unavailable (for example, a stdio server has no URL) are omitted.
+    """
+    properties: dict[str, str] = {}
+    name = getattr(tool, "name", None)
+    if isinstance(name, str) and name:
+        properties[MCP_SERVER_NAME_PROPERTY] = name
+    url = _sanitize_mcp_server_url(getattr(tool, "url", None))
+    if url:
+        properties[MCP_SERVER_URL_PROPERTY] = url
+    return properties
+
+
 def _normalize_mcp_name(name: str) -> str:
     """Normalize MCP tool/prompt names to allowed identifier pattern (A-Za-z0-9_.-)."""
     return re.sub(r"[^A-Za-z0-9_.-]", "-", name)
@@ -3253,6 +3295,7 @@ async def _load_tools_locked(self) -> None:
                         _MCP_REMOTE_NAME_KEY: tool.name,
                         _MCP_NORMALIZED_NAME_KEY: normalized_name,
                         _MCP_IS_TOOL_KEY: True,
+                        **_mcp_server_identity_properties(self),
                     },
                 )
                 new_functions.append(func)

python/packages/core/agent_framework/observability.py

@@ -348,6 +348,9 @@ class OtelAttr(str, Enum):
     MCP_METHOD_NAME = "mcp.method.name"
     MCP_PROTOCOL_VERSION = "mcp.protocol.version"
     MCP_SESSION_ID = "mcp.session.id"
+    # Identity of the MCP server an MCP-served tool call was routed to (set on execute_tool spans).
+    TOOL_SERVER_NAME = "microsoft.tool.server.name"
+    URL_FULL = "url.full"
     PROMPT_NAME = "gen_ai.prompt.name"
     NETWORK_TRANSPORT = "network.transport"
     NETWORK_PROTOCOL_NAME = "network.protocol.name"
@@ -2689,6 +2692,13 @@ def run(
 # region Otel Helpers
 
 
+# ``FunctionTool.additional_properties`` keys under which an MCP-served function carries the identity of the
+# MCP server it calls. ``get_function_span_attributes`` reads them to stamp ``microsoft.tool.server.name`` and
+# ``url.full`` on the ``execute_tool`` span. The URL is stored already stripped of credentials and query string.
+MCP_SERVER_NAME_PROPERTY = "_mcp_server_name"
+MCP_SERVER_URL_PROPERTY = "_mcp_server_url"
+
+
 def get_function_span_attributes(function: FunctionTool, tool_call_id: str | None = None) -> dict[str, str]:
     """Get the span attributes for the given function.
 
@@ -2707,6 +2717,13 @@ def get_function_span_attributes(function: FunctionTool, tool_call_id: str | Non
     }
     if function.description:
         attributes[OtelAttr.TOOL_DESCRIPTION] = function.description
+    properties = function.additional_properties or {}
+    server_name = properties.get(MCP_SERVER_NAME_PROPERTY)
+    if isinstance(server_name, str) and server_name:
+        attributes[OtelAttr.TOOL_SERVER_NAME] = server_name
+    server_url = properties.get(MCP_SERVER_URL_PROPERTY)
+    if isinstance(server_url, str) and server_url:
+        attributes[OtelAttr.URL_FULL] = server_url
     return attributes
 
 

python/packages/core/tests/core/test_mcp_observability.py

@@ -510,3 +510,85 @@ async def test_mcp_spans_not_created_when_observability_disabled(span_exporter:
 
 
 # endregion
+
+
+# region execute_tool server identity
+
+
+@pytest.mark.parametrize(
+    ("raw", "expected"),
+    [
+        ("https://user:pw@mcp.example.com:8443/api/mcp?code=secret#frag", "https://mcp.example.com:8443/api/mcp"),
+        ("http://localhost/mcp", "http://localhost/mcp"),
+        ("https://[::1]:9000/mcp?x=1", "https://[::1]:9000/mcp"),
+        ("ftp://example.com/mcp", None),
+        ("not a url", None),
+        ("", None),
+        (None, None),
+    ],
+)
+def test_sanitize_mcp_server_url(raw: str | None, expected: str | None):
+    from agent_framework._mcp import _sanitize_mcp_server_url
+
+    assert _sanitize_mcp_server_url(raw) == expected
+
+
+def test_mcp_server_identity_properties_for_http_tool():
+    from agent_framework._mcp import _mcp_server_identity_properties
+    from agent_framework.observability import MCP_SERVER_NAME_PROPERTY, MCP_SERVER_URL_PROPERTY
+
+    tool = MCPStreamableHTTPTool(name="weather", url="https://mcp.example.com/mcp?key=secret")
+
+    assert _mcp_server_identity_properties(tool) == {
+        MCP_SERVER_NAME_PROPERTY: "weather",
+        MCP_SERVER_URL_PROPERTY: "https://mcp.example.com/mcp",
+    }
+
+
+def test_mcp_server_identity_properties_for_stdio_tool_omits_url():
+    from agent_framework._mcp import _mcp_server_identity_properties
+    from agent_framework.observability import MCP_SERVER_NAME_PROPERTY
+
+    tool = MCPStdioTool(name="local", command="python")
+
+    assert _mcp_server_identity_properties(tool) == {MCP_SERVER_NAME_PROPERTY: "local"}
+
+
+def test_function_span_attributes_include_mcp_server_identity():
+    from agent_framework import FunctionTool
+    from agent_framework.observability import (
+        MCP_SERVER_NAME_PROPERTY,
+        MCP_SERVER_URL_PROPERTY,
+        get_function_span_attributes,
+    )
+
+    function = FunctionTool(
+        name="get_weather",
+        description="",
+        func=lambda: "ok",
+        additional_properties={
+            MCP_SERVER_NAME_PROPERTY: "weather",
+            MCP_SERVER_URL_PROPERTY: "https://mcp.example.com/mcp",
+        },
+    )
+
+    attributes = get_function_span_attributes(function, "call-1")
+
+    assert attributes[OtelAttr.TOOL_SERVER_NAME] == "weather"
+    assert attributes[OtelAttr.URL_FULL] == "https://mcp.example.com/mcp"
+    assert attributes[OtelAttr.TOOL_NAME] == "get_weather"
+
+
+def test_function_span_attributes_omit_server_identity_for_plain_function():
+    from agent_framework import FunctionTool
+    from agent_framework.observability import get_function_span_attributes
+
+    function = FunctionTool(name="plain", description="", func=lambda: "ok")
+
+    attributes = get_function_span_attributes(function, "call-1")
+
+    assert OtelAttr.TOOL_SERVER_NAME not in attributes
+    assert OtelAttr.URL_FULL not in attributes
+
+
+# endregion