Read, write, format, and create tables in Excel .xlsx files via @negokaz/excel-mcp-server (npx) — Go binary, no dependencies

@negokaz/excel-mcp-server v0.12.0 — verified recipe

Install & run:

npm install --prefix /tmp/excel @negokaz/excel-mcp-server
# Binary at: node_modules/@negokaz/excel-mcp-server/dist/excel-mcp-server_darwin_arm64_v8.0/excel-mcp-server
# Or use launcher: node_modules/@negokaz/excel-mcp-server/dist/launcher.js (auto-selects platform binary)
# Zero runtime deps — compiled Go binary for all platforms (darwin/linux/windows × amd64/arm64)

6 tools (5 working, 1 crashes):

Key observations from 31 verified calls across 3 sessions:

1. Go binary, not Node.js — compiled via goreleaser for 8 platform/arch combos. launcher.js is a Node shim that auto-selects the right binary. Ultra-fast (sub-2ms per call).
2. ⚠️ Cannot create new .xlsx files — fileAbsolutePath must point to an EXISTING .xlsx. Tool returns "no such file or directory" otherwise. Create a minimal xlsx first (any empty Excel file works).
3. `newSheet: true` creates sheets within an existing file — works reliably. Use this to add new sheets.
4. Output is HTML tables — not JSON or CSV. Responses include <table>, <th>, <td> tags with column headers (A, B, C...) and row numbers.
5. Formulas stored as text — =B2*C2 is written and read back as the formula string. Excelize doesn't compute formulas (that's Excel/LibreOffice's job). showFormula: true renders them in output.
6. `showStyle: true` returns YAML-like style definitions with ref IDs (e.g., f1, l1) and style-ref attributes on <td> elements.
7. Unicode works — Turkish İ, ç, ö, ü, ş all round-trip correctly.
8. `excel_describe_sheets` returns JSON with usedRange, tables[], pivotTables[], pagingRanges[] per sheet.

⚠️ Critical gotchas:

• `excel_copy_sheet` CRASHES the server — nil pointer dereference in excelize/v2.(*File).copySheet (Go panic, SIGSEGV). Confirmed in 2 separate runs. The server dies and all subsequent calls fail with "Not connected". Do not use this tool.
• `excel_format_range` requires 2D styles array for multi-cell ranges — styles: {font: {bold: true}} on range "A1:C1" fails with "number of style columns in row 0 (1) does not match range size (3)". Correct syntax: styles: [[{font:{bold:true}}, {font:{bold:true}}, {font:{bold:true}}]]
• Single-cell range works with flat object — range: "A1:A1" accepts styles: {font: {bold: true}} directly
• Fill color requires `fgColor` with "FF" ARGB prefix — {fill: {type: "pattern", pattern: "solid", fgColor: "FF4472C4"}} works. Using color instead of fgColor returns "$first: string is invalid". Pattern must be one of: none, solid, mediumGray, darkGray, lightGray, darkHorizontal, darkVertical, darkDown, darkUp, darkGrid, darkTrellis, lightHorizontal, lightVertical, lightDown, lightUp, lightGrid, lightTrellis, gray125, gray0625
• Minimal xlsx requirement — The file must have a valid <dimension> element and <sharedStrings> XML part. A bare-minimum Python-generated xlsx with these elements works; an overly minimal one without them causes "failed to update dimension: invalid range format"

Real trace (write + read round-trip):

→ excel_write_to_sheet({fileAbsolutePath: "/tmp/test.xlsx", sheetName: "Sheet1",
   range: "A1:D4", values: [["Product","Qty","Price","Total"],["Wid