check_file_exists

Verify if a file exists at a specified path to prevent errors in automated workflows. This tool confirms file presence before proceeding with operations.

Instructions

检查文件是否存在。参数: filepath (文件路径)

Input Schema

TableJSON Schema

Name	Required	Description	Default
`filepath`	Yes

Implementation Reference

src/wxauto_mcp/wxauto_mcp/api_files.py:175-210 (handler)

Main implementation of the check_file_exists tool. Decorated with @tool for registration (lines 175-178), the handler function (lines 179-210) validates the filepath, checks if the file exists using Path, and returns JSON-formatted results with file metadata (exists, is_file, size, absolute path).

@tool(
    name="check_file_exists",
    description="检查文件是否存在。参数: filepath (文件路径)"
)
def check_file_exists(filepath: str) -> str:
    """
    检查文件是否存在

    Args:
        filepath: 文件路径

    Returns:
        JSON 格式的检查结果
    """
    if not filepath:
        return format_result(False, "文件路径不能为空")

    try:
        path = Path(filepath)
        exists = path.exists()
        is_file = path.is_file() if exists else False
        size = path.stat().st_size if exists and is_file else None

        return format_result(
            True,
            f"文件{'存在' if exists else '不存在'}",
            {
                "exists": exists,
                "is_file": is_file,
                "size": size,
                "path": str(path.absolute())
            }
        )
    except Exception as e:
        logger.error(f"检查文件失败: {e}")
        return format_result(False, f"检查文件失败: {e}")

src/wxauto_mcp/wxauto_mcp/api_files.py:175-178 (registration)
Tool registration using the @tool decorator. Registers the function with name 'check_file_exists' and provides a description: '检查文件是否存在。参数: filepath (文件路径)'
```
@tool(
    name="check_file_exists",
    description="检查文件是否存在。参数: filepath (文件路径)"
)
```

src/wxauto_mcp/wxauto_mcp/utils.py:14-31 (helper)

format_result helper function used by check_file_exists to format the operation result as a JSON string with success status, message, and optional data fields.

def format_result(success: bool, message: str, data: Optional[dict[str, Any]] = None) -> str:
    """
    格式化操作结果为 JSON 字符串

    Args:
        success: 操作是否成功
        message: 结果消息
        data: 附加数据

    Returns:
        JSON 格式的结果字符串
    """
    result = {
        "success": success,
        "message": message,
        "data": data or {},
    }
    return json.dumps(result, ensure_ascii=False, indent=2)

src/wxauto_mcp/wxauto_mcp/rpc.py:51-80 (registration)

The @tool decorator implementation that registers functions as MCP tools. Applies output limiting, registers the tool in TOOL_REGISTRY, and returns the original function unmodified.

def tool(name: Optional[str] = None, description: Optional[str] = None) -> Callable:
    """
    工具装饰器

    注册函数为 MCP 工具，自动应用输出限制。

    Args:
        name: 工具名称，默认使用函数名
        description: 工具描述

    Returns:
        装饰后的函数
    """

    def decorator(func: Callable) -> Callable:
        # 应用输出限制
        limited_func = limit_output(func)

        # 注册到工具注册表
        tool_name = name or func.__name__
        TOOL_REGISTRY.register(
            name=tool_name,
            func=limited_func,
            description=description or func.__doc__ or "",
        )

        # 返回原函数，不修改其行为
        return func

    return decorator

src/wxauto_mcp/wxauto_mcp/rpc.py:25-48 (helper)

limit_output decorator applied to all tools via @tool to limit output size to MAX_OUTPUT_SIZE (50000 characters) to prevent returning excessive data.

def limit_output(func: Callable) -> Callable:
    """
    输出限制装饰器

    限制工具输出的最大长度，防止返回过大的数据。

    Args:
        func: 被装饰的函数

    Returns:
        包装后的函数
    """

    @wraps(func)
    def wrapper(*args: Any, **kwargs: Any) -> str:
        result = func(*args, **kwargs)
        if isinstance(result, str) and len(result) > MAX_OUTPUT_SIZE:
            logger.warning(
                f"{func.__name__} 输出超过限制 ({len(result)} > {MAX_OUTPUT_SIZE})，已截断"
            )
            return result[:MAX_OUTPUT_SIZE] + f"\n... (输出已截断，原始大小: {len(result)} 字符)"
        return result

    return wrapper

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