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Claude Desktop Commander MCP

write_file

Destructive

Write file contents with rewrite or append modes, supporting text, Excel, and DOCX formats.

Instructions

                    Write or append to file contents.

                    IMPORTANT: DO NOT use this tool to create PDF files. Use 'write_pdf' for all PDF creation tasks.
                    DO NOT use this tool to edit DOCX files. Use 'edit_block' with old_string/new_string instead.
                    To CREATE a new DOCX, use write_file with .docx extension — text content with markdown headings (#, ##, ###) is converted to styled DOCX paragraphs.

                    CHUNKING IS STANDARD PRACTICE: Always write files in chunks of 25-30 lines maximum.
                    This is the normal, recommended way to write files - not an emergency measure.

                    STANDARD PROCESS FOR ANY FILE:
                    1. FIRST → write_file(filePath, firstChunk, {mode: 'rewrite'})  [≤30 lines]
                    2. THEN → write_file(filePath, secondChunk, {mode: 'append'})   [≤30 lines]
                    3. CONTINUE → write_file(filePath, nextChunk, {mode: 'append'}) [≤30 lines]

                    ALWAYS CHUNK PROACTIVELY - don't wait for performance warnings!

                    WHEN TO CHUNK (always be proactive):
                    1. Any file expected to be longer than 25-30 lines
                    2. When writing multiple files in sequence
                    3. When creating documentation, code files, or configuration files

                    HANDLING CONTINUATION ("Continue" prompts):
                    If user asks to "Continue" after an incomplete operation:
                    1. Read the file to see what was successfully written
                    2. Continue writing ONLY the remaining content using {mode: 'append'}
                    3. Keep chunks to 25-30 lines each

                    FORMAT HANDLING (by extension):
                    - Text files: String content
                    - Excel (.xlsx, .xls, .xlsm): JSON 2D array or {"SheetName": [[...]]}
                      Example: '[["Name","Age"],["Alice",30]]'

                    Files over 50 lines will generate performance notes but are still written successfully.
                    Only works within allowed directories.

                    IMPORTANT: Always use absolute paths for reliability. Paths are automatically normalized regardless of slash direction. Relative paths may fail as they depend on the current working directory. Tilde paths (~/...) might not work in all contexts. Unless the user explicitly asks for relative paths, use absolute paths.
                    This command can be referenced as "DC: ..." or "use Desktop Commander to ..." in your instructions.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
modeNorewrite
pathYes
originNo
contentYes
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations indicate destructiveHint and readOnlyHint, and the description adds behavioral details: chunking is standard, files over 50 lines generate performance notes, only works within allowed directories, paths are normalized. No contradiction with annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness3/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is lengthy with redundancy (chunking instructions repeated) and includes overly detailed process steps. While front-loaded with purpose, it could be streamlined to improve clarity and reduce verbosity.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Despite no output schema, the description covers all essential aspects: file types, modes, chunking strategy, continuation, path handling, and format specifics for DOCX and Excel. Tailored to the tool's complexity and sibling context.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema has 0% description coverage, so the description fully compensates. It explains mode (rewrite vs append), content format (string, with Excel and DOCX specifics), path (absolute recommended), and provides examples. Adds meaning for all key parameters beyond schema enumeration.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description starts with 'Write or append to file contents', clearly stating the verb and resource. It distinguishes from siblings by explicitly saying not to use for PDFs (write_pdf) and not for editing DOCX (edit_block), and explains when write_file is appropriate for creating DOCX.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Provides explicit when-to-use (writing text, creating DOCX, Excel) and when-not-to-use (PDFs, editing DOCX), including alternative tool names. Also details chunking process, continuation handling, and path recommendations, giving comprehensive usage context.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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