Excel MCP Server

Write range

write_range

Destructive

Writes values into Excel worksheet cells, overwriting existing content. Use it to fill ranges with text, numbers, booleans, dates, or safe formulas.

Instructions

Write values into cells, overwriting what is there.

Values can be text, numbers, booleans or null (to empty a cell). Text starting with '=' is a formula, e.g. '=SUM(B2:B9)'; formulas that reach the network, other programs or other workbooks are rejected. Text in the form '2026-01-31' or '2026-01-31T09:30:00' is stored as a date. Send long numeric IDs as text so they keep all their digits.

Input Schema

TableJSON Schema

Name	Required	Description
`path`	Yes	Path to an .xlsx, .xlsm, .xltx or .xltm file. Relative paths are resolved in the server's workbook directory when one is configured; otherwise use an absolute path.
`rows`	Yes	Rows of values written right and down from start_cell.
`sheet`	Yes	Worksheet name, e.g. 'Sheet1'.
`start_cell`	Yes	A single cell in A1 notation, e.g. 'B2'.

Output Schema

TableJSON Schema

Name	Required	Description	Default
`range`	Yes
`sheet`	Yes
`cells_written`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Addedv1.1.1Sep 29, 2026

TDQS

A4.1/5.0

Behavior4/5

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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the overwrite risk is partly covered. The description goes further, disclosing formula acceptance and the rejection of formulas that reach the network/other programs/workbooks, date-string coercion, and the long-numeric-ID pitfall — meaningful behavioral context beyond the annotations.

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

Conciseness4/5

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

Front-loaded with the primary action and consequence, then a compact list of value-type rules. Every sentence earns its place; slightly list-like but no filler.

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

Completeness4/5

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

An output schema exists and annotations carry the safety profile, so the description need not explain return values. It covers value types, formulas, dates and ID handling well, leaving only the missing sibling routing (clear_range) as a minor gap.

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

Parameters4/5

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

Schema coverage is 100%, so the baseline is 3. The description earns above baseline by explaining the value semantics of the rows payload (text/number/boolean/null, '=' formula detection, date-string storage), which the schema only enumerates as types without meaning.

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?

States a specific verb and resource ('Write values into cells') and immediately names the scope constraint ('overwriting what is there'). This cleanly distinguishes it from read_range, copy_range and clear_range without opening either schema.

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

Usage Guidelines3/5

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

The description implies when to use it (writing/overwriting cells) but names no alternatives or exclusions. Notably, it does not tell the agent when to prefer clear_range over writing nulls, and there is no guidance on preconditions such as file existence or sheet presence.

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