fix duplicate names between supplied tools and mcp servers (#4649)

python/packages/ag-ui/agent_framework_ag_ui/_orchestration/_tooling.py

@@ -8,6 +8,7 @@ import logging
 from typing import TYPE_CHECKING, Any
 
 from agent_framework import BaseChatClient
+from agent_framework._tools import _append_unique_tools  # pyright: ignore[reportPrivateUsage]
 
 if TYPE_CHECKING:
     from agent_framework import SupportsAgentRun
@@ -22,7 +23,7 @@ def _collect_mcp_tool_functions(mcp_tools: list[Any]) -> list[Any]:
         mcp_tools: List of MCP tool instances.
 
     Returns:
-        List of functions from connected MCP tools.
+        Functions from connected MCP tools.
     """
     functions: list[Any] = []
     for mcp_tool in mcp_tools:
@@ -56,7 +57,11 @@ def collect_server_tools(agent: SupportsAgentRun) -> list[Any]:
     # Include functions from connected MCP tools (only available on Agent)
     mcp_tools = getattr(agent, "mcp_tools", None)
     if mcp_tools:
-        server_tools.extend(_collect_mcp_tool_functions(mcp_tools))
+        _append_unique_tools(
+            server_tools,
+            _collect_mcp_tool_functions(mcp_tools),
+            duplicate_error_message="Tool names must be unique. Consider setting `tool_name_prefix` on the MCPTool.",
+        )
 
     logger.info(f"[TOOLS] Agent has {len(server_tools)} configured tools")
     for tool in server_tools:
@@ -109,26 +114,13 @@ def merge_tools(server_tools: list[Any], client_tools: list[Any] | None) -> list
         logger.info("[TOOLS] No client tools - not passing tools= parameter (using agent's configured tools)")
         return None
 
-    server_tool_names = {getattr(tool, "name", None) for tool in server_tools}
-    unique_client_tools = [tool for tool in client_tools if getattr(tool, "name", None) not in server_tool_names]
-
-    if not unique_client_tools:
-        # Same check: must pass server tools if any require approval
-        if server_tools and _has_approval_tools(server_tools):
-            logger.info(
-                f"[TOOLS] Client tools duplicate server but server has approval tools - "
-                f"passing {len(server_tools)} server tools for approval mode"
-            )
-            return server_tools
-        logger.info("[TOOLS] All client tools duplicate server tools - not passing tools= parameter")
-        return None
-
-    combined_tools: list[Any] = []
-    if server_tools:
-        combined_tools.extend(server_tools)
-    combined_tools.extend(unique_client_tools)
+    combined_tools = _append_unique_tools(
+        list(server_tools),
+        client_tools,
+        duplicate_error_message="Tool names must be unique.",
+    )
     logger.info(
         f"[TOOLS] Passing tools= parameter with {len(combined_tools)} tools "
-        f"({len(server_tools)} server + {len(unique_client_tools)} unique client)"
+        f"({len(server_tools)} server + {len(client_tools)} client)"
     )
     return combined_tools

python/packages/ag-ui/tests/ag_ui/test_tooling.py

@@ -2,6 +2,7 @@
 
 from unittest.mock import MagicMock
 
+import pytest
 from agent_framework import Agent, tool
 
 from agent_framework_ag_ui._orchestration._tooling import (
@@ -20,7 +21,8 @@ class DummyTool:
 class MockMCPTool:
     """Mock MCP tool that simulates connected MCP tool with functions."""
 
-    def __init__(self, functions: list[DummyTool], is_connected: bool = True) -> None:
+    def __init__(self, functions: list[DummyTool], is_connected: bool = True, name: str = "mock-mcp") -> None:
+        self.name = name
         self.functions = functions
         self.is_connected = is_connected
 
@@ -45,11 +47,8 @@ def test_merge_tools_filters_duplicates() -> None:
     server = [DummyTool("a"), DummyTool("b")]
     client = [DummyTool("b"), DummyTool("c")]
 
-    merged = merge_tools(server, client)
-
-    assert merged is not None
-    names = [getattr(t, "name", None) for t in merged]
-    assert names == ["a", "b", "c"]
+    with pytest.raises(ValueError, match="Duplicate tool name 'b'"):
+        merge_tools(server, client)
 
 
 def test_register_additional_client_tools_assigns_when_configured() -> None:
@@ -131,6 +130,17 @@ def test_collect_server_tools_with_mcp_tools_via_public_property() -> None:
     assert len(tools) == 2
 
 
+def test_collect_server_tools_raises_on_duplicate_agent_and_mcp_tool_names() -> None:
+    duplicate_tool = DummyTool("regular_tool")
+    mock_mcp = MockMCPTool([duplicate_tool], is_connected=True, name="docs-mcp")
+
+    agent = _create_chat_agent_with_tool("regular_tool")
+    agent.mcp_tools = [mock_mcp]
+
+    with pytest.raises(ValueError, match="Duplicate tool name 'regular_tool'"):
+        collect_server_tools(agent)
+
+
 # Additional tests for tooling coverage
 
 
@@ -176,11 +186,11 @@ def test_merge_tools_no_client_tools() -> None:
 
 
 def test_merge_tools_all_duplicates() -> None:
-    """merge_tools returns None when all client tools duplicate server tools."""
+    """merge_tools raises when client and server tools share a name."""
     server = [DummyTool("a"), DummyTool("b")]
     client = [DummyTool("a"), DummyTool("b")]
-    result = merge_tools(server, client)
-    assert result is None
+    with pytest.raises(ValueError, match="Duplicate tool name 'a'"):
+        merge_tools(server, client)
 
 
 def test_merge_tools_empty_server() -> None:
@@ -208,7 +218,7 @@ def test_merge_tools_with_approval_tools_no_client() -> None:
 
 
 def test_merge_tools_with_approval_tools_all_duplicates() -> None:
-    """merge_tools returns server tools with approval mode even when client duplicates."""
+    """merge_tools raises even when a client tool duplicates an approval-gated server tool."""
 
     class ApprovalTool:
         def __init__(self, name: str):
@@ -217,7 +227,5 @@ def test_merge_tools_with_approval_tools_all_duplicates() -> None:
 
     server = [ApprovalTool("write_doc")]
     client = [DummyTool("write_doc")]  # Same name as server
-    result = merge_tools(server, client)
-    assert result is not None
-    assert len(result) == 1
-    assert result[0].approval_mode == "always_require"
+    with pytest.raises(ValueError, match="Duplicate tool name 'write_doc'"):
+        merge_tools(server, client)