Command-Line MCP Server

Instructions

Implementation Reference

• src/cmd_line_mcp/server.py:404-479 (handler)

  Implementation of the get_command_help handler function.

  async def get_command_help() -> dict[str, Any]:
      """
      Get detailed help about command capabilities and usage.
  
      This tool provides comprehensive information about:
      - Supported commands in each category (read, write, system)
      - Blocked commands for security reasons
      - Command chaining capabilities (pipes, semicolons, ampersands)
      - Usage restrictions and examples
  
      Returns:
          A dictionary with detailed information about command capabilities and usage
      """
      # Get the latest command lists and separator support
      command_lists = self.config.get_effective_command_lists()
      separator_support = self.config.has_separator_support()
  
      # Log the separator support for debugging
      logger.info(f"Separator support status: {separator_support}")
      logger.info(
          f"allow_command_separators setting: {self.config.get('security', 'allow_command_separators')}"
      )
  
      # Extra check for pipe character in dangerous patterns
      pipe_in_patterns = any(
          "|" in p or r"\|" in p for p in command_lists["dangerous_patterns"]
      )
      logger.info(
          f"Pipe character found in dangerous patterns: {pipe_in_patterns}"
      )
  
      # Update capabilities
      updated_capabilities = {
          "supported_commands": {
              "read": command_lists["read"],
              "write": command_lists["write"],
              "system": command_lists["system"],
          },
          "blocked_commands": command_lists["blocked"],
          "command_chaining": {
              "pipe": (
                  "Supported" if separator_support["pipe"] else "Not supported"
              ),
              "semicolon": (
                  "Supported"
                  if separator_support["semicolon"]
                  else "Not supported"
              ),
              "ampersand": (
                  "Supported"
                  if separator_support["ampersand"]
                  else "Not supported"
              ),
          },
          "command_restrictions": "Special characters like $(), ${}, backticks, and I/O redirection are blocked",
      }
  
      # Provide helpful information for Claude to understand command usage
      return {
          "capabilities": updated_capabilities,
          "examples": self.usage_examples,
          "recommended_approach": {
              "finding_large_files": "Use 'du -h <directory>/* | sort -hr | head -n 10' to find the 10 largest files",
              "file_searching": "Use 'find <directory> -type f -name \"pattern\"' for file searches",
              "text_searching": "Use 'grep \"pattern\" <file>' to search in files",
              "file_viewing": "Use 'cat', 'head', or 'tail' for viewing files",
              "sorting": "Use 'sort' with options like -n (numeric), -r (reverse), -h (human readable sizes)",
              "text_processing": "Use 'awk' for advanced text processing. For example: 'ls -la | awk \"{print $1, $9}\"' to show permissions and filenames",
              "column_filtering": "Use 'awk' to filter by column values: 'cat data.txt | awk \"{if($3 > 100) print}\"' to show lines where column 3 exceeds 100",
          },
          "permissions": {
              "read_commands": "Can be executed without confirmation",
              "write_commands": "Require approval for first use in a session",
              "system_commands": "Require approval for first use in a session",
          },
      }