microsoft/autogen · error · ValueError

Unsupported tool type: {type(tool)}

Error message

Unsupported tool type: {type(tool)}

What it means

Raised in AzureAIAgent's tool-conversion loop when a tools entry is neither a string, a ToolDefinition, a Tool, nor a callable. The converter dispatches on type; anything else (dict, None, a dataclass, a string variable that's actually a schema) hits the else branch and raises with the offending type name.

Source

Thrown at python/packages/autogen-ext/src/autogen_ext/agents/azure/_azure_ai_agent.py:452

                # elif tool == "sharepoint_grounding":
                #     converted_tools.append(SharepointToolDefinition())  # type: ignore
                else:
                    raise ValueError(f"Unsupported tool string: {tool}")
            elif isinstance(tool, ToolDefinition):
                converted_tools.append(tool)
            elif isinstance(tool, Tool):
                self._original_tools.append(tool)
                converted_tools.append(self._convert_tool_to_function_tool_definition(tool))
            elif callable(tool):
                if hasattr(tool, "__doc__") and tool.__doc__ is not None:
                    description = tool.__doc__
                else:
                    description = ""
                function_tool = FunctionTool(tool, description=description)
                self._original_tools.append(function_tool)
                converted_tools.append(self._convert_tool_to_function_tool_definition(function_tool))
            else:
                raise ValueError(f"Unsupported tool type: {type(tool)}")

    def _convert_tool_to_function_tool_definition(self, tool: Tool) -> FunctionToolDefinition:
        """
        Convert an autogen Tool to an Azure AI Agent function tool definition.

        Args:
            tool (Tool): The AutoGen tool to convert

        Returns:
            models.FunctionToolDefinition: A function tool definition compatible with Azure AI Agent API
        """

        schema = tool.schema
        parameters: Dict[str, object] = {}

        if "parameters" in schema:
            parameters = {
                "type": schema["parameters"]["type"],

View on GitHub (pinned to 027ecf0a37)

Solutions

1. Wrap function schemas in FunctionTool/Tool instances or pass callables; let the agent convert them.
2. If you have an Azure SDK ToolDefinition, import it from the same azure-ai-projects package version the agent uses so isinstance checks pass.
3. Sanitize the list before construction: filter None and reject non-(str|ToolDefinition|Tool|callable) entries with a clear error.

Example fix

# before
tools=[{"type":"function","function":{"name":"f","parameters":{...}}}]
# after
from autogen_core.tools import FunctionTool
tools=[FunctionTool(func, description="f", name="f")]

allowed = (str, ToolDefinition, Tool)
invalid = [t for t in tools if not (isinstance(t, allowed) or callable(t))]
if invalid:
    raise TypeError(f"Unsupported tool entries: {[type(t).__name__ for t in invalid]}")

def is_valid_tool_entry(tool) -> bool:
    return isinstance(tool, (str, ToolDefinition, Tool)) or callable(tool)

try:
    agent = AzureAIAgent(client, tools=tools)
except ValueError as e:
    if "Unsupported tool type" in str(e):
        tools = [wrap_as_function_tool(t) for t in tools]
        agent = AzureAIAgent(client, tools=tools)

When it happens

Trigger: Passing raw OpenAI-style JSON tool dicts (e.g. {"type":"function","function":{...}}), None entries, or ORM/dataclass objects in the tools list at construction or via set_tools.

Common situations: Porting code from the raw OpenAI/Azure REST API or other agent frameworks that use dict tool specs; a tools list built dynamically where one element is None; passing a ToolDefinition from a mismatched SDK version that no longer isinstance-checks.

Related errors

• Unsupported tool string: {tool}
• The tool '{tool_call.name}' is not available.
• File search is not enabled for this assistant. Add a file_se
• Thread not initialized
• Agent not initialized

AI-assisted analysis of microsoft/autogen@027ecf0a37 (2026-08-15). Data as JSON: /api/errors/f56e41cc7dbd4b01. Report an issue: GitHub.