Excel MCP Server

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write_file

Write data to CSV or Excel files with support for multiple sheets, enabling structured data export from the Excel MCP Server.

Instructions

Write data to a new CSV or Excel file (supports multiple sheets for Excel)

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "filePath": "<filePath>"
    },
    "name": "write_file"
  }
}

Input Schema

Name	Required	Description
`filePath`	Yes	Path for the new file (must end with .csv, .xlsx, or .xls)
`data`	No	Array of arrays representing rows of data (single sheet mode)
`headers`	No	Optional headers for the first row (single sheet mode)
`sheet`	No	Sheet name for Excel files (single sheet mode, defaults to "Sheet1")
`sheets`	No	Array of sheet objects for multi-sheet Excel files

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Jan 2, 2026

TDQS

C2.9/5.0

Behavior2/5

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It mentions file creation and format support but fails to address critical behaviors: whether it overwrites existing files, requires specific permissions, handles errors, or has rate limits. For a write operation, this leaves significant gaps in understanding its impact and constraints.

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

Conciseness5/5

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

The description is a single, efficient sentence that front-loads the core purpose and key capability (multi-sheet support). There is no wasted verbiage, making it easy to parse and understand at a glance.

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

Completeness2/5

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

For a write tool with no annotations and no output schema, the description is incomplete. It lacks details on file overwriting behavior, error handling, format-specific constraints, and response structure. Given the complexity of 5 parameters and the absence of structured safety hints, more context is needed for reliable use.

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

Parameters3/5

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

Schema description coverage is 100%, so the schema fully documents all 5 parameters. The description adds minimal value beyond the schema by implying parameter usage modes (e.g., single vs. multi-sheet), but doesn't clarify mutual exclusivity or provide examples. Baseline 3 is appropriate given the schema's comprehensive coverage.

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

Purpose4/5

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

The description clearly states the action ('Write data') and target resource ('to a new CSV or Excel file'), with the specific capability of supporting multiple sheets for Excel. It distinguishes itself from sibling tools like 'read_file' by specifying a write operation, though it doesn't explicitly differentiate from 'write_multi_sheet' beyond mentioning multi-sheet support.

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

Usage Guidelines2/5

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

The description provides no guidance on when to use this tool versus alternatives like 'write_multi_sheet' or 'add_sheet', nor does it mention prerequisites or exclusions. It lacks context for choosing between single-sheet and multi-sheet modes, leaving usage decisions ambiguous.

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