BerriAI/litellm · error · ValueError

Missing required parameter: name

Error message

Missing required parameter: name

What it means

For Anthropic hosted tools (types in ANTHROPIC_HOSTED_TOOLS, e.g. web_search, code_execution), LiteLLM requires a 'name' — read from tool['name'] or tool['function']['name'] — and it must be a string. If neither location holds a string name, this ValueError aborts request transformation.

Source

Thrown at litellm/llms/anthropic/chat/transformation.py:712

            if _display_width_px is None or _display_height_px is None:
                raise ValueError("Missing required parameter: display_width_px or display_height_px")

            _computer_tool: Final = AnthropicComputerTool(
                type=tool["type"],
                name=tool["function"].get("name", "computer"),
                display_width_px=_display_width_px,
                display_height_px=_display_height_px,
            )

            _display_number: Final = tool["function"]["parameters"].get("display_number")
            if _display_number is not None:
                _computer_tool["display_number"] = _display_number

            returned_tool = _computer_tool
        elif any(tool["type"].startswith(t) for t in ANTHROPIC_HOSTED_TOOLS):
            function_name_obj: Final = tool.get("name", tool.get("function", {}).get("name"))
            if function_name_obj is None or not isinstance(function_name_obj, str):
                raise ValueError("Missing required parameter: name")
            function_name: Final = function_name_obj

            additional_tool_params: Final = {}
            for k, v in tool.items():
                if k != "type" and k != "name":
                    additional_tool_params[k] = v

            returned_tool = AnthropicHostedTools(
                type=tool["type"],
                name=function_name,
                **additional_tool_params,
            )
        elif tool["type"] == "url":  # mcp server tool
            mcp_server = AnthropicMcpServerTool(**tool)
        elif tool["type"] == "mcp":
            mcp_server = self._map_openai_mcp_server_tool(cast(OpenAIMcpServerTool, tool))
        elif tool["type"] == "tool_search_tool_regex_20251119":
            # Tool search tool using regex

View on GitHub (pinned to 6c2dcb801b)

Solutions

1. Include a string 'name' for hosted tools, either at the top level or under 'function'.
2. Use the conventional name for the tool family (e.g. 'web_search', 'code_execution') or match Anthropic's docs.
3. If the tool came from the Anthropic SDK, pass it through as-is rather than rebuilding it without name.
4. Pre-validate hosted tools have a string name before calling completion().

Example fix

# before
tools = [{"type": "web_search_20250305", "max_uses": 3}]

# after
tools = [{"type": "web_search_20250305", "name": "web_search", "max_uses": 3}]

def validate_hosted_tools(tools, hosted_types):
    for t in tools:
        if any(str(t.get("type", "")).startswith(h) for h in hosted_types):
            name = t.get("name") or t.get("function", {}).get("name")
            if not isinstance(name, str) or not name:
                raise ValueError(f"hosted tool '{t['type']}' missing string 'name'")
    return tools

def hosted_tool_has_name(tool) -> bool:
    name = tool.get("name") or tool.get("function", {}).get("name")
    return isinstance(name, str) and len(name) > 0

When it happens

Trigger: Passing a hosted tool like {'type': 'web_search_20250305'} with no name at either level, or with name set to a non-string (dict, None, number); mixing OpenAI-style {'type': 'function', 'function': {...}} shapes with Anthropic hosted tool types.

Common situations: Porting raw Anthropic SDK tool dicts (which use {'type': 'web_search_20250305', 'name': 'web_search'}) through code that strips the top-level name; schemas generated by other frameworks that omit name for non-function tools.

Related errors

• Missing required parameter: parameters
• Missing required parameter: display_width_px or display_heig
• Tool search tool must have a valid name
• Advisor tool must have a valid model
• Unsupported tool type: {tool['type']}

AI-assisted analysis of BerriAI/litellm@6c2dcb801b (2026-08-15). Data as JSON: /api/errors/af12333bc5d93e1d. Report an issue: GitHub.