tail_file
Read the last lines of a text file to monitor logs or check recent content. Specify the number of lines and file path for efficient file viewing.
Instructions
Read the last N lines of a text file.
Args:
path: Path to the file
lines: Number of lines to read (default: 10)
encoding: Text encoding (default: utf-8)
ctx: MCP context
Returns:
Last N lines of the fileInput Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| path | Yes | ||
| lines | No | ||
| encoding | No | utf-8 |
Implementation Reference
- mcp_filesystem/server.py:351-374 (handler)MCP tool handler for 'tail_file'. This is the entrypoint function decorated with @mcp.tool(), defining the input schema via type annotations and docstring, handling errors, and delegating to the operations layer.
@mcp.tool() async def tail_file( path: str, ctx: Context, lines: int = 10, encoding: str = "utf-8", ) -> str: """Read the last N lines of a text file. Args: path: Path to the file lines: Number of lines to read (default: 10) encoding: Text encoding (default: utf-8) ctx: MCP context Returns: Last N lines of the file """ try: components = get_components() content = await components["operations"].tail_file(path, lines, encoding) return content except Exception as e: return f"Error reading file: {str(e)}" - mcp_filesystem/operations.py:458-493 (helper)Core implementation of tail_file in the FileOperations class. Performs path validation, reads the entire file content, splits into lines, and returns the last N lines.
async def tail_file( self, path: Union[str, Path], lines: int = 10, encoding: str = "utf-8" ) -> str: """Read the last N lines of a text file. Args: path: Path to the file lines: Number of lines to read (default: 10) encoding: Text encoding (default: utf-8) Returns: Last N lines of the file Raises: ValueError: If path is outside allowed directories FileNotFoundError: If file does not exist """ abs_path, allowed = await self.validator.validate_path(path) if not allowed: raise ValueError(f"Path outside allowed directories: {path}") try: # We need to read the whole file to get the last N lines # This could be optimized for very large files data = await anyio.to_thread.run_sync(abs_path.read_text, encoding) file_lines = data.splitlines() start = max(0, len(file_lines) - lines) return "\n".join(file_lines[start:]) except FileNotFoundError: raise FileNotFoundError(f"File not found: {path}") except PermissionError: raise ValueError(f"Permission denied: {path}") except UnicodeDecodeError: raise ValueError(f"Cannot decode file as {encoding}: {path}") - mcp_filesystem/server.py:351-351 (registration)The @mcp.tool() decorator registers the tail_file function as an MCP tool.
@mcp.tool()