Excel MCP Server An open-source Model Context Protocol (MCP) server that lets Claude, Cursor, VS Code Copilot, Codex and other AI clients create, read and edit Excel files: charts, PivotTables, formulas, tables and more. It is built on openpyxl, needs no Microsoft Excel, and runs on Windows, macOS and Linux. Install and try it at excelmcpserver.com, or see Quick start below. Features Charts and PivotTables Create…
An open-source Model Context Protocol (MCP) server that lets
Claude, Cursor, VS Code Copilot, Codex and other AI clients create, read and edit Excel files:
charts, PivotTables, formulas, tables and more. It is built on openpyxl, needs no Microsoft
Excel, and runs on Windows, macOS and Linux.
Create Excel charts with AI: column, bar, line, area, pie, doughnut, radar, scatter and
bubble, with combos, secondary axes, trendlines and error bars
The Excel 2016 chart types: waterfall, histogram, Pareto, box and whisker, treemap, sunburst
and funnel
Real PivotTables that Excel refreshes (grouping, calculated fields, “show values as”,
layouts, filters), plus slicers and timelines for PivotTables and tables
Sparklines (line, column, win/loss)
Formulas and dynamic arrays
Formulas are calculated without Excel by a built-in engine (479 functions, checked
against more than 25,000 formulas recorded from real Excel), so read_range returns values
for files that were never opened in Excel
Dynamic arrays (FILTER, SORT, UNIQUE, SEQUENCE, LET) are stored as Excel stores
them and spill into the cells next to them
Find out why a number is wrong: trace precedents and dependents across sheets, names and
tables, and evaluate a formula step by step as Excel’s Evaluate Formula does
Goal Seek: change an input until a formula reaches the value you want
Data, tables and rules
Read and write cells, dates and hyperlinks; tables with totals rows and calculated columns
Conditional formatting (scales, data bars, icon sets, top/bottom, duplicates, text, dates),
data validation (dropdowns, limits, input messages)
Sort, filter (with criteria), find and replace, remove duplicates, text to columns, fill
series, paste special
Fonts, fills, borders, number formats, merged cells, frozen panes, grouping, print setup,
sheet protection, images, notes and defined names. Inserting or deleting rows and columns
updates every reference, as in Excel
Large files
Reads stream the workbook and return pages, so memory stays flat on sheets with hundreds of
thousands of rows; every call is bounded by size and cell limits
Edits of a sheet of 1 MB of XML or more parse only the rows they touch, so inserting or
deleting rows and columns, sorting, replacing, copying a sheet and creating a PivotTable
take seconds on a 200,000-row sheet instead of minutes
Macros (opt-in)
Read the VBA code in .xlsm files. Writing VBA is off unless you start the server with
--allow-vba-write, which also decides whether create_workbook and import_workbook may
make .xlsm/.xltm files; the server never runs macros
Safe by design
Optional folder confinement, a formula safety check, read-only mode, localhost-only HTTP by
default, and atomic saves that never leave a half-written file
Works with .xlsx, .xlsm (macros are preserved), .xltx and .xltm files. Existing
threaded comments, shapes, form controls and other content the tools cannot edit are kept as
they are.
Quick start
You need uv. Every client runs the
server with uvx excel-mcp-server stdio; replace /path/to/workbooks with the folder the
server may use. excelmcpserver.com has the same steps with copy
buttons and one-click install links for Cursor and VS Code.
Claude Desktop (Chat): download
excel-mcp-server.mcpb
from the latest release and open it. Claude asks which folder the server may use.
Claude Code (the CLI, and the Code tab in Claude Desktop):
claude mcp add excel --scope user -- uvx excel-mcp-server stdio --allow-dir /path/to/workbooks
Cursor (~/.cursor/mcp.json), and most clients that use an mcpServers config:
Claude Desktop, manual setup: open Settings, Developer, Edit Config, add the mcpServers
JSON above to claude_desktop_config.json, and restart Claude.
Desktop apps often cannot find uvx, because they do not see your shell’s PATH (common
on macOS). Use its full path instead, which which uvx prints.
Choosing which files it can use
With --allow-dir DIR, the server only opens workbooks inside DIR (subfolders included)
and relative paths such as reports/q1.xlsx start there. Repeat the flag to allow several
folders, or set EXCEL_FILES_PATH (separate folders with : on macOS/Linux and ; on
Windows).
Without --allow-dir, any absolute path to an Excel file works. In every mode the server
only touches Excel files and never silently overwrites an existing workbook.
Clients connect to http://127.0.0.1:8017/mcp. Workbooks live in the --allow-dir folder
(default ./excel_files), and export_workbook / import_workbook move files between the
server and the client.
The server listens on localhost only. To accept other machines, set a token and a host:
Add tools that write VBA macros (see warning below); ignored with --read-only
--tools AREAS
EXCEL_MCP_TOOLS
all
Only offer the core tools and these comma-separated areas, to save context (see Choosing tools)
--max-file-mb N
EXCEL_MCP_MAX_FILE_MB
100
Largest workbook the server opens. Also sets the unpacked-size limit (10 times this) that every opened or uploaded workbook must stay under; parts compressed over 500:1 are refused
--max-cells N
EXCEL_MCP_MAX_CELLS
100000
Most cells one call may read, write or format; reads are still returned in pages; also bounds text to 256 characters per cell on average
--max-pivot-cells N
EXCEL_MCP_MAX_PIVOT_CELLS
3000000
Largest PivotTable source in cells (a 230,000-row, 13-column sheet); creating one from the biggest sources takes a minute and about 2 GB of memory
--max-loaded-cells N
EXCEL_MCP_MAX_LOADED_CELLS
3000000
Most cells and rows of a workbook that may be loaded into memory at once, about 0.5 KB each (a 3,000,000 limit is about 1.5 GB). A workbook with more is refused by the tools that must load whole sheets; read_range and the other streaming reads, and edits of large sheets that parse only some rows, are not limited by the size of the sheet. It also limits, to 128 characters per cell, the formula text that shared formulas expand to
read_vba; with --allow-vba-write: write_vba_module, delete_vba_module
Choosing tools
Every tool costs context in every request. --tools offers only the core tools
(describe_workbook, describe_sheet, read_range) and the areas you list, for example
uvx excel-mcp-server stdio --tools data,charts. It combines with --read-only (read-only tools
of the areas) and --allow-vba-write (which also needs the vba area). An unknown area stops the
server at startup and lists the valid ones. The sizes are characters of tool descriptions and
schemas, at about 3.5 characters per token:
read_vba; with --allow-vba-write: write_vba_module, delete_vba_module
1,900
CSV
import_csv reads a .csv or .tsv file into a sheet (created if missing) at a cell, and
export_csv writes a range as CSV. Both stay in the allowed folders, within --max-cells and
--max-file-mb, and never run anything.
Import detects the delimiter from the first record (or takes comma, semicolon, tab,
pipe) and reads UTF-8 with or without a BOM, UTF-16 and cp1252. Quoted fields and line
breaks inside them are kept.
Fields are typed as in Excel’s import: numbers (also 1,234.50, 12%; decimal for a
decimal comma), TRUE/FALSE and ISO dates (2026-01-31, 2026-01-31 09:30) become values.
Text Excel would alter stays text: leading zeros (007), more than 15 digits, a leading +,
and numeric dates such as 01/02/2026, which are read only in the date_order you name
(dmy or mdy). as_text keeps every field as text.
Fields are never formulas. Text starting with =, +, - or @ is stored as text with
Excel’s quote prefix, so editing the cell does not run it; a number such as -5 is a number.
Export writes raw values (full precision, ISO dates) or, with formatted, what Excel shows.
Text cells starting with =, +, - or @ get a ' prefix (escape_formulas, on by
default) so a spreadsheet that opens the file does not run them; numbers are never prefixed.
Datetimes are written as 2026-01-31T09:30:00, which Excel opens as text; use formatted
for Excel.
Use encoding: utf-8-sig for a BOM, which Excel needs to show accents when it opens a UTF-8
file by double-click. Lines end with CRLF.
Every parameter is documented in TOOLS.md. Parameters mean the same in every tool:
Parameter
Meaning
path, sheet
The workbook and the worksheet
range, at
A block of cells (A1:D20), and the top-left cell of whatever is placed there: written values, copies, charts, images, PivotTables, slicers
source
Where data comes from, optionally on another sheet (Data!A1:E200)
name
The name of a table, chart, image, PivotTable, slicer or defined name
_cm, _pt, _chars
Units of sizes: width_cm, row_heights_pt, column_widths_chars
Tools that change a workbook return what they changed (sheet, range, name) so that the
next call can refer to it. Charts and images are selected by name, as listed by describe_sheet.
Writing macros (opt-in)
With --allow-vba-write (or EXCEL_MCP_ALLOW_VBA_WRITE=1) the server can set the code of
standard, class, workbook and sheet modules in .xlsm and .xltm files, delete standard and
class modules, and create or import .xlsm/.xltm workbooks (without the option both are
refused, and import_workbook removes macros from uploads to .xlsx/.xltx). The server only
stores the code; it never runs it, and Excel asks before enabling macros. Digitally signed VBA projects are
refused, since any change would invalidate the signature.
Warning: macro code runs with your user’s rights once you enable macros in Excel. A
model that reads untrusted content could be tricked into writing harmful code. Enable this
option only for trusted workflows, keep --allow-dir narrow, and read the code before
you enable macros. The tools are never offered in --read-only mode.
Security
Formulas are parsed before they are written. Functions that reach the network or other
programs (WEBSERVICE, IMAGE, RTD, CALL, Google Sheets IMPORTXML and others),
Excel 4.0 macro functions (FILES, GET.WORKBOOK, RUN and others), DDE links and
references to other workbooks are rejected. HYPERLINK is accepted with a fixed
http(s)://, mailto: or #Sheet!A1 link only.
Paths are resolved, including symlinks, before they are checked against the allowed
folders. Network (UNC) and Windows device paths are always rejected.
A single call processes at most 100,000 cells (--max-cells) and, on average, 256 characters of text per cell (25.6 million characters at the default), and large reads are returned in pages. Text a workbook stores once but many cells hold is counted in every cell, and a workbook that saving would expand past the unpacked-size limit is refused.
Cell contents are data from files. The server tells the model not to follow instructions
found in them, but review what an assistant does with workbooks from untrusted sources.
Please report vulnerabilities privately; see SECURITY.md.
Limitations
Formulas are stored in the file, and Excel calculates them when it opens it. So that
read_range is useful before that, values mode calculates formulas that have no saved
result with a built-in calculator (479 functions: math, statistics and distributions,
regression, database, engineering, financial and bond, dates, text, lookup, logical, LET and
LAMBDA, sorting and filtering). Results Excel saved are
always preferred. A formula the calculator cannot reproduce exactly as Excel does (an
unsupported function, a circular reference, or an Excel quirk it does not replicate) is
returned as null and listed in uncalculated with the reason; it is never guessed.
Ranges in a formula are reduced to the formula’s own row or column where Excel’s ordinary
(not array-entered) formulas do the same, and volatile functions such as RAND are not
calculated. The calculator is checked against more than 2,500 formulas recorded from real
Excel (tests/fixtures/formula_golden.json).
trace_formula and goal_seek use that calculator, so goal_seek refuses a formula it
cannot calculate. Where Excel’s Trace Precedents shows the cells an OFFSET starts from,
trace_formula shows the cells INDIRECT and OFFSET point at; when those cannot be
worked out the formula is listed in unknown. Where Excel’s search stops at the
“may not have found a solution” message, goal_seek may still find a root, and it stores
the answer only when it converges (within 0.001 of the target, as Excel does).
Functions Excel added after 2007 (IFS, XLOOKUP, STDEV.S, SORT, …) are written
with the _xlfn. prefix Excel expects, wherever formulas are stored (cells, copied and
sorted cells, conditional formats, data validation, defined names).
Legacy .xls files are not supported; use import_csv for CSV files.
PivotTables are created from a snapshot and can use text, number and date columns of up to
3,000,000 cells (--max-pivot-cells); Excel refreshes them from the live source data. They support number formats,
“show values as” (percent of total, row, column or parent, difference from, running total,
rank), sorting by label or value, date and number grouping, calculated fields, compact,
outline and tabular layouts, subtotals on or off, filters with chosen items and several
value fields as columns or rows. The figures written into the cells are the ones Excel shows
after a refresh, checked against about 200 PivotTables recorded from real Excel
(tests/fixtures/pivot_golden.json). The exceptions: items that tie when sorted by value may
swap places on refresh, and values_in: "rows" cannot be combined with rank figures or, with
subtotals, other figures along a field, because Excel mixes the value fields up there.
add_slicer adds slicers (Insert > Slicer) for tables and PivotTables, and timelines for date
fields of PivotTables: field, caption, position and size, columns, style, sort, selected
items (or a period) and “hide items with no data”. Selecting items filters as clicking
does: table rows are filtered and hidden; PivotTable items are hidden and the figures
recalculated from the source, which Excel confirms on refresh (about 200 PivotTables are
checked against Excel, and the slicer variants against Excel’s own results). One slicer can
filter several PivotTables that share a cache, such as those of copied sheets. Limits: a
PivotTable made or refreshed by Excel keeps its figures in the cells (the hidden items and
a refresh-on-open mark are stored, so Excel recalculates when it opens the file); fields
grouped in a PivotTable take no slicer.
Inserting or deleting rows and columns, and renaming a sheet, update references like
Excel. Hyperlink targets and 3D references (Sheet1:Sheet3!A1) are left alone (Excel does
the same). An edit that cuts through an array formula, a PivotTable, a table header or two
tables at once is refused. Inserted cells take the formatting, row height and column width
of the line above or to the left (nothing at the first row or column), and calculated table
columns are filled into rows inserted in a table.
Editing a workbook keeps what the tools cannot change: sparklines, extended conditional
formats and validation, slicers and timelines, newer charts (waterfall, histogram,
treemap and others), threaded comments, shapes, form controls, linked data types and
custom XML stay as Excel saved them and move with inserted or deleted rows and columns and
renamed sheets. copy_sheet copies sparklines, slicers and timelines (as Excel does), the Excel
2010 half of conditional formats (data bars, icon sets) and the Excel 2016 charts made by
create_chart, but not the others. Deleting a sheet removes slicers that only it used;
slicers that would be left without their PivotTable block the deletion, and deleting a
table, or the column a table slicer filters, removes the slicer.
Digital signatures are removed, as Excel does when a signed file changes.
Formulas that return several values (FILTER, SORT, UNIQUE, SEQUENCE, A2:A9*2) are
stored as dynamic array formulas, as Excel stores them, and spill into the cells next to
them. A cell in the way blocks the spill (Excel shows #SPILL!), and write_range
reports it. Where the calculator cannot tell how large a result is, only the formula’s
cell is stored and Excel fills in the rest when it opens the file.
Upgrading from 1.x
Version 2.0 makes tool and parameter names consistent across tools, which breaks 1.x clients
and saved prompts. The changelog has a table that maps every 1.x name to its 2.0 replacement:
Upgrading from 1.x. Coming from 0.x? See the
1.0.0 notes first.
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