Read contents from files and URLs.
                    Read PDF files and extract content as markdown and images.
                    
                    Suitable for reading authorized local files directly without starting a shell command.
                    
                    Supports partial file reading with:
                    - 'offset' (start line, default: 0)
                      * Positive: Start from line N (0-based indexing)
                      * Negative: Read last N lines from end (tail behavior)
                    - 'length' (max lines to read, default: configurable via 'fileReadLineLimit' setting, initially 1000)
                      * Used with positive offsets for range reading
                      * Ignored when offset is negative (reads all requested tail lines)
                    
                    Examples:
                    - offset: 0, length: 10     → First 10 lines
                    - offset: 100, length: 5    → Lines 100-104
                    - offset: -20               → Last 20 lines  
                    - offset: -5, length: 10    → Last 5 lines (length ignored)
                    
                    Performance optimizations:
                    - Large files with negative offsets use reverse reading for efficiency
                    - Large files with deep positive offsets use byte estimation
                    - Small files use fast readline streaming
                    
                    When reading from the file system, only works within allowed directories.
                    Can fetch content from URLs when isUrl parameter is set to true
                    (URLs are always read in full regardless of offset/length).
                    
                    FORMAT HANDLING (by extension):
                    - Text: Uses offset/length for line-based pagination
                    - Excel (.xlsx, .xls, .xlsm): Returns JSON 2D array
                      * sheet: "Sheet1" (name) or "0" (index as string, 0-based)
                      * range uses FROM:TO format (e.g., "A1:D100", "C1:C1", "B2:B50")
                      * offset/length work as row pagination (optional fallback)
                    - Images (PNG, JPEG, GIF, WebP): Base64 encoded viewable content
                    - PDF: Extracts text content as markdown with page structure
                      * offset/length work as page pagination (0-based)
                      * Includes embedded images when available
                    - DOCX (.docx): Two modes depending on parameters:
                      * DEFAULT (no offset/length): Returns a text-bearing outline — shows paragraphs with text,
                        tables with cell content, styles, image refs. Skips shapes/drawings/SVG noise.
                        Each element shows its body index [0], [1], etc.
                      * WITH offset/length: Returns raw pretty-printed XML with line pagination.
                        Use this to drill into specific sections or see the actual XML for editing.
                      * Raw DOCX XML output is compatible with edit_block's XML find/replace mode using
                        XML fragments copied from the read output.
                      * Raw XML mode requires a non-zero offset (offset=1 starts from line 1).
                        offset=0 returns the outline regardless of length.
                      * Bulk transformations can be performed programmatically against the DOCX archive
                        when the task requires changes across many XML text nodes.

                    Paths refer to the selected device. Relative paths depend on that device's current working directory, and tilde paths (~/...) may not resolve in every context. Absolute paths are generally the most reliable.
                    This command can be referenced as "DC: ..." or "use Desktop Commander to ..." in your instructions.