run-llama/llama_index · error · ValueError

metadata must be provided

Error message

metadata must be provided

What it means

Error "metadata must be provided" thrown in run-llama/llama_index.

Source

Thrown at llama-index-core/llama_index/core/tools/function_tool.py:124

        # Determine if the function requires context by inspecting its signature
        fn_to_inspect = fn or async_fn
        assert fn_to_inspect is not None
        sig = inspect.signature(fn_to_inspect)
        self.requires_context = any(
            _is_context_param(param.annotation) for param in sig.parameters.values()
        )
        self.ctx_param_name = (
            next(
                param.name
                for param in sig.parameters.values()
                if _is_context_param(param.annotation)
            )
            if self.requires_context
            else None
        )

        if metadata is None:
            raise ValueError("metadata must be provided")
        self._metadata = metadata

        # Handle callback (sync and async)
        self._callback = None
        if callback is not None:
            self._callback = callback
        elif async_callback is not None:
            self._callback = async_to_sync(async_callback)

        self._async_callback = None
        if async_callback is not None:
            self._async_callback = async_callback
        elif self._callback is not None:
            self._async_callback = sync_to_async(self._callback)

        self.partial_params = partial_params or {}

        # Extract actual default values from FieldInfo defaults so they are

View on GitHub (pinned to afd0fef371)

Solutions

1. Provide metadata (ToolMetadata) for the tool.
2. Use FunctionTool.from_defaults which derives metadata from the function signature.

When it happens

Trigger: Thrown at llama-index-core/llama_index/core/tools/function_tool.py:124 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of run-llama/llama_index@afd0fef371 (2026-08-15). Data as JSON: /api/errors/dc9535bd6555f3ad. Report an issue: GitHub.