# Excel MCP Server (FsOpenXmlDsl) (nuget · Kookerella.FsOpenXmlDsl.Mcp)

Excel tools for AI agents: read/write, decompile to F#/C#/XML/JSON, or build from XML/JSON.

- Trust score: 83/100 (high trust)
- Change this week: +3
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-09-20

## Components

- nuget · `Kookerella.FsOpenXmlDsl.Mcp`: 83/100 (this document), [markdown](https://verifymcp.io/servers/marknicholls-fsopenxmldsl-mcp/kookerella-fsopenxmldsl-mcp.md), [page](https://verifymcp.io/servers/marknicholls-fsopenxmldsl-mcp/kookerella-fsopenxmldsl-mcp)

## Channel facts

- Registry: `nuget`
- Package: `Kookerella.FsOpenXmlDsl.Mcp`
- Version: `0.6.4`
- Transport: `stdio`

## Trust breakdown

How this component scores in each security and reliability category. Every signal is checked automatically from public evidence about the published package, including repeated runs of it in an isolated sandbox, and we only credit what we can confirm. Scores are 0–100 per category. Scoring method: https://verifymcp.io/docs/scoring (what has changed: https://verifymcp.io/docs/scoring/changelog)

Scored 2026-09-20.

- **Supply Chain Security**: 100/100
  - No malware found by supply-chain analysis.
  - No known CVEs affecting this package version or its production dependencies.
  - No install/post-install scripts declared.
  - No production dependencies, so there is no dependency health to assess.
- **Provenance & Transparency**: 45/100
  - Source repository is publicly reachable at the declared URL.
  - Provenance check failed: no build-provenance attestation is published.
  - Clear OSI-approved license (MIT).
  - Actively maintained (last published 15 days ago).
  - Disclosure check failed: no security disclosure policy was found in the source repository.
- **Schema Quality & AI Usability**: 71/100
  - AI-judged instruction clarity (excellent).
  - Context-footprint check failed: tool/resource definitions use about 1850 tokens (~185/item across 10 items; 10 tools + 0 resources), over budget; trim descriptions and params.
  - Usage-examples check failed: none of the tools include examples.
- **Stability & Change Management**: 93/100
  - Stability observed for 28 of 30 days with no destabilising changes; credit accrues until the full window elapses.
- **Tool Coverage**: 100/100
  - 100% of tools have a non-trivial description (not blank, and not just the tool's name).
  - 100% of tool parameters carry a description.
- **Tool Safety**: 100/100
  - No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.
  - We read all 10 captured tool definition(s), and no name or description among them implies an irreversible operation.
  - An AI judge read all 10 captured unit(s) of tool text and found none that tries to manipulate the model reading it.
- **Capabilities**: 100/100
  - Implements a current MCP spec version (2026-07-28).

## Install

### How do I install the Excel MCP Server (FsOpenXmlDsl) server?

Excel MCP Server (FsOpenXmlDsl) runs locally as a NuGet package, launched with dnx Kookerella.FsOpenXmlDsl.Mcp@0.6.4 --yes. Ready-made configuration for Claude, Cursor, VS Code, Codex and 3 more is on this page, copied from each client's own documentation.

### Claude

```bash
claude mcp add marknicholls-fsopenxmldsl-mcp -- dnx Kookerella.FsOpenXmlDsl.Mcp@0.6.4 --yes
```

### Cursor

```json
{
  "mcpServers": {
    "marknicholls-fsopenxmldsl-mcp": {
      "command": "dnx",
      "args": [
        "Kookerella.FsOpenXmlDsl.Mcp@0.6.4",
        "--yes"
      ]
    }
  }
}
```

### VS Code

```json
{
  "servers": {
    "marknicholls-fsopenxmldsl-mcp": {
      "command": "dnx",
      "args": [
        "Kookerella.FsOpenXmlDsl.Mcp@0.6.4",
        "--yes"
      ]
    }
  }
}
```

### Codex

```bash
codex mcp add marknicholls-fsopenxmldsl-mcp -- dnx Kookerella.FsOpenXmlDsl.Mcp@0.6.4 --yes
```

### opencode

```json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "marknicholls-fsopenxmldsl-mcp": {
      "type": "local",
      "command": [
        "dnx",
        "Kookerella.FsOpenXmlDsl.Mcp@0.6.4",
        "--yes"
      ],
      "enabled": true
    }
  }
}
```

### Hermes

```yaml
mcp_servers:
  marknicholls-fsopenxmldsl-mcp:
    command: "dnx"
    args: ["Kookerella.FsOpenXmlDsl.Mcp@0.6.4", "--yes"]
```

### Netclaw

```json
{
  "McpServers": {
    "marknicholls-fsopenxmldsl-mcp": {
      "Transport": "stdio",
      "Command": "dnx",
      "Arguments": [
        "Kookerella.FsOpenXmlDsl.Mcp@0.6.4",
        "--yes"
      ]
    }
  }
}
```

### Other

```json
{
  "mcpServers": {
    "marknicholls-fsopenxmldsl-mcp": {
      "command": "dnx",
      "args": [
        "Kookerella.FsOpenXmlDsl.Mcp@0.6.4",
        "--yes"
      ]
    }
  }
}
```

## Changelog

Every change recorded for this component, newest first. Days that predate change tracking, or that we cannot explain, say so: "we were watching and nothing happened" and "we were not watching" are different claims.

### 2026-09-20 (score 83, +1)

No change was recorded against any check on this day. Stability & Change Management went from 90 to 93. That category is still filling its 30-day observation window: 27 days of observed history at the previous scan, 28 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-18 (score 82, +1)

No change was recorded against any check on this day. Stability & Change Management went from 83 to 87. That category is still filling its 30-day observation window: 25 days of observed history at the previous scan, 26 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-15 (score 81, +1)

No change was recorded against any check on this day. Stability & Change Management went from 73 to 77. That category is still filling its 30-day observation window: 22 days of observed history at the previous scan, 23 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-13 (score 80, +1)

No change was recorded against any check on this day. Stability & Change Management went from 67 to 70. That category is still filling its 30-day observation window: 20 days of observed history at the previous scan, 21 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-11 (score 79, +1)

No change was recorded against any check on this day. Stability & Change Management went from 60 to 63. That category is still filling its 30-day observation window: 18 days of observed history at the previous scan, 19 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-09 (score 78, +1)

No change was recorded against any check on this day. Stability & Change Management went from 53 to 57. That category is still filling its 30-day observation window: 16 days of observed history at the previous scan, 17 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-07 (score 77, +1)

No change was recorded against any check on this day. Stability & Change Management went from 47 to 50. That category is still filling its 30-day observation window: 14 days of observed history at the previous scan, 15 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-06 (score 76, +15)

- [security improvement] Malware scan: unverified → pass

## MCP tools (10)

### `generate_fsharp_script` (~147 tokens)

Reads an existing Excel workbook and returns a self-contained F# script (using Kookerella.FsOpenXmlDsl) that rebuilds an equivalent file when run via `dotnet fsi`. Useful for explaining how a file is structured, or as a starting point for a caller who wants the library's full feature set (styling, tables, charts, pivot tables, etc.) beyond what create_workbook exposes.

Input parameters:

- `outputFileName` (string, required): The output filename the generated script should save its rebuilt file to, e.g. "output.xlsx".
- `path` (string, required): Path to an existing .xlsx/.xlsm file to reverse-engineer into F# source.

### `generate_json_schema` (~156 tokens)

Returns the raw JSON Schema (Json.schema.json) that generate_json's output and create_workbook_from_json's input both conform to. Meant for a caller authoring JSON by hand or by a generation script who wants real schema validation/autocomplete in their own editor or pipeline, rather than reverse-engineering the shape from a generate_json example. This schema isn't validated against at runtime by the core library itself the way Xml.xsd is (JSON Schema has no .NET-built-in equivalent to System.Xml.Schema, so wiring that up would mean adding a runtime dependency - JsonSchema.Net - to every consumer of the core library just for this) - it's bundled here, in the Mcp tool specifically, purely to hand back on request.

### `generate_csharp_script` (~244 tokens)

Reads an existing Excel workbook and returns a self-contained C# file (using Kookerella.CsOpenXmlDsl) that rebuilds an equivalent file when run via `dotnet run <file>.cs` (.NET 10's file-based apps feature - no .csproj needed). The C# equivalent of generate_fsharp_script, for a caller who wants pasteable/runnable C# rather than F# - useful for explaining how a file is structured, or as a starting point for the wrapper's fluent API (styling, tables, charts, pivot tables, sparklines, conditional formatting, data validation, hyperlinks, comments, print settings, defined names, protection, etc. - Kookerella.CsOpenXmlDsl now covers the same worksheet/workbook-level feature set as generate_fsharp_script's own Kookerella.FsOpenXmlDsl) beyond what create_workbook exposes.

Input parameters:

- `outputFileName` (string, required): The output filename the generated script should save its rebuilt file to, e.g. "output.xlsx".
- `path` (string, required): Path to an existing .xlsx/.xlsm file to reverse-engineer into C# source.

### `create_workbook_from_json` (~236 tokens)

Builds a new Excel workbook from JSON matching the shape generate_json produces (see the main library repo's Json.schema.json) and saves it to disk - the inverse of generate_json. The JSON-side equivalent of create_workbook_from_xml, for a caller that already produces data as JSON and wants to reach Excel without learning the OOXML schema, this library's own F#/C# API, or needing .NET installed at all - the .NET work happens inside this server, so any language can call it directly, and a human with no MCP client at all can get the same result via `fsopenxmldsl-mcp build` from a plain shell. Covers the same worksheet/workbook-level feature set generate_json does; unlike create_workbook, this isn't limited to plain cell values - styling, tables, charts, and every other modeled feature can be expressed in the JSON.

Input parameters:

- `json` (string, required): The workbook JSON content - an object matching Json.schema.json's root shape.
- `path` (string, required): Output file path, e.g. "C:\reports\invoice.xlsx". The directory must already exist.

### `generate_json` (~196 tokens)

Reads an existing Excel workbook and returns it as JSON. The JSON-side equivalent of generate_xml, for a caller whose tooling speaks JSON rather than XML - same use cases (inspect, transform, or archive a workbook's structure without any F#/C# source, or any .NET runtime at all, on the caller's side) and the same worksheet/workbook-level feature set. Usable directly from Python, JavaScript, or any other language, and a human with no MCP client at all can get the same result via `fsopenxmldsl-mcp convert <file> --lang json` from a plain shell. Unlike generate_xml, there's no runtime JSON Schema validation built into the core library itself (see generate_json_schema's own doc string for why) - but generate_json_schema still returns the documented shape this produces.

Input parameters:

- `path` (string, required): Path to an existing .xlsx/.xlsm file to convert to JSON.

### `create_workbook_from_xml` (~248 tokens)

Builds a new Excel workbook from XML matching Kookerella.FsOpenXmlDsl's own embedded schema (Xml.xsd) and saves it to disk - the inverse of generate_xml. The natural target for a caller that already produces data as XML (e.g. an XSLT pipeline generating a report) and wants to reach Excel without learning the OOXML schema, this library's own F#/C# API, or needing .NET installed at all - like generate_xml, the .NET work happens inside this server, so any language can call it directly, and a human with no MCP client at all can get the same result via `fsopenxmldsl-mcp build` from a plain shell. Covers the same worksheet/workbook-level feature set generate_xml does; unlike create_workbook, this isn't limited to plain cell values - styling, tables, charts, and every other modeled feature can be expressed in the XML.

Input parameters:

- `path` (string, required): Output file path, e.g. "C:\reports\invoice.xlsx". The directory must already exist.
- `xml` (string, required): The workbook XML content - a <workbook> root element matching Xml.xsd.

### `generate_xml` (~224 tokens)

Reads an existing Excel workbook and returns it as XML, validated against Kookerella.FsOpenXmlDsl's own embedded schema (Xml.xsd). A plain-data alternative to generate_fsharp_script/generate_csharp_script for a caller who wants to inspect, transform (e.g. via XSLT), or archive a workbook's structure without any F#/C# source involved - and without any .NET runtime on the caller's side either: the .NET work happens inside this server, so Python, JavaScript, or any other language can call this tool directly, and a human with no MCP client at all can get the same result via `fsopenxmldsl-mcp convert <file> --lang xml` from a plain shell. Unlike those two, this returns data, not a runnable script, so there is no output-filename parameter to control what a rebuild saves as. Covers the same worksheet/workbook-level feature set generate_fsharp_script does.

Input parameters:

- `path` (string, required): Path to an existing .xlsx/.xlsm file to convert to XML.

### `generate_xml_schema` (~86 tokens)

Returns the raw XSD (Xml.xsd) that generate_xml's output and create_workbook_from_xml's input both conform to. Meant for a caller authoring XML by hand or by transform (e.g. an XSLT stylesheet) who wants real schema validation/autocomplete in their own editor or pipeline, rather than reverse- engineering the shape from a generate_xml example.

### `read_workbook` (~119 tokens)

Reads an existing Excel workbook (.xlsx/.xlsm) and returns its sheets and cell contents as JSON. Formula cells are rendered as "=expression" (matching create_workbook's input convention), with any cached value included separately under CachedValue. Features outside the core cell model (charts, tables, pivot tables, styling, etc.) are not included in this output - see MAPPING.md in the main library repo for the full list of what round-trips.

Input parameters:

- `path` (string, required): Path to an existing .xlsx or .xlsm file.

### `create_workbook` (~194 tokens)

Creates a new Excel workbook (.xlsx) from a simple grid of sheets/rows/cells and saves it to disk. Each cell is given as plain text, the same way you'd type it into Excel: a leading '=' makes it a formula (e.g. "=SUM(A1:A2)"), 'true'/'false' makes a boolean, a bare number is numeric, and anything else is text. Rows don't need to be the same length. Does not support cell styling, tables, charts, or pivot tables in this version - reference the Kookerella.FsOpenXmlDsl library directly for those.

Input parameters:

- `path` (string, required): Output file path, e.g. "C:\reports\invoice.xlsx". The directory must already exist.
- `sheets` (array, required): The sheets to create, in order. Each sheet has a Name and a Rows grid (array of rows, each an array of cell text).

## Diagnostics

Captured diagnostic sections: Provenance, Dependencies. The full working is on the page: https://verifymcp.io/servers/marknicholls-fsopenxmldsl-mcp/kookerella-fsopenxmldsl-mcp#diagnostics

## Score history

- 2026-09-20: 83
- 2026-09-19: 82
- 2026-09-18: 82
- 2026-09-17: 81
- 2026-09-16: 81
- 2026-09-15: 81
- 2026-09-14: 80
- 2026-09-13: 80
- 2026-09-12: 79
- 2026-09-11: 79
- 2026-09-10: 78
- 2026-09-09: 78
- 2026-09-08: 77
- 2026-09-07: 77
- 2026-09-06: 76
- 2026-09-05: 61
- 2026-09-04: 75
- 2026-09-03: 75
- 2026-09-02: 74
- 2026-09-01: 74
- 2026-08-31: 74
- 2026-08-30: 73
- 2026-08-29: 73
- 2026-08-28: 72
- 2026-08-27: 57
- 2026-08-26: 57
- 2026-08-25: 70
- 2026-08-24: 70
- 2026-08-23: 70

## Common questions

### What is the Excel MCP Server (FsOpenXmlDsl) server?

Excel MCP Server (FsOpenXmlDsl) is listed in the public MCP registry as io.github.MarkNicholls/fsopenxmldsl-mcp. Excel tools for AI agents: read/write, decompile to F#/C#/XML/JSON, or build from XML/JSON. This page covers its NuGet package (Kookerella.FsOpenXmlDsl.Mcp).

### Is the Excel MCP Server (FsOpenXmlDsl) server safe to use?

Excel MCP Server (FsOpenXmlDsl) scores 83 out of 100 on VerifyMCP. We found no known CVEs affecting it as of 20 September 2026. It declares no install or post-install scripts. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.

### What tools does the Excel MCP Server (FsOpenXmlDsl) server expose?

Excel MCP Server (FsOpenXmlDsl) exposes 10 tools: generate_fsharp_script, generate_json_schema, generate_csharp_script, create_workbook_from_json, generate_json, and 5 more. Their descriptions and schemas cost roughly 1,850 tokens of context every time the server is loaded.

### Is the Excel MCP Server (FsOpenXmlDsl) server still maintained?

Excel MCP Server (FsOpenXmlDsl) is still listed as active in the MCP registry. We last reached this channel on 20 September 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.

### What licence is the Excel MCP Server (FsOpenXmlDsl) server under?

Excel MCP Server (FsOpenXmlDsl) declares the MIT licence, which is OSI-approved. That covers the source only, and says nothing about the cost of any service it calls.

## Links

- NuGet package: https://www.nuget.org/packages/Kookerella.FsOpenXmlDsl.Mcp
- Socket report: https://socket.dev/nuget/package/Kookerella.FsOpenXmlDsl.Mcp
- Repository: https://github.com/Kookerella-Ltd/Kookerella.FsOpenXmlDsl
- Website: https://github.com/Kookerella-Ltd/Kookerella.FsOpenXmlDsl/tree/master/src/Kookerella.FsOpenXmlDsl.Mcp
- Changelog RSS feed: https://verifymcp.io/servers/marknicholls-fsopenxmldsl-mcp/kookerella-fsopenxmldsl-mcp.xml
- Changelog JSON feed: https://verifymcp.io/servers/marknicholls-fsopenxmldsl-mcp/kookerella-fsopenxmldsl-mcp.json
- HTML version of this page: https://verifymcp.io/servers/marknicholls-fsopenxmldsl-mcp/kookerella-fsopenxmldsl-mcp