Install formulon-mcp

formulon-mcp is published to npm and runs unmodified through npx. Most MCP clients only need a one-line registration.

Node.js 22+ is required

The server uses Node 22 features. Earlier versions will fail to start. Check with node --version.

Claude Code

claude mcp add --scope user formulon -- npx -y @libraz/formulon-mcp

Verify with:

claude mcp list

formulon should report ✓ Connected. If it does not, the Claude Code docs include logs and troubleshooting steps.

Project scope

The command above uses --scope user, which registers formulon for every project. To scope it to a single repository instead, write a .mcp.json file in the project root:

{
  "mcpServers": {
    "formulon": {
      "command": "npx",
      "args": ["-y", "@libraz/formulon-mcp"]
    }
  }
}

Claude Code picks up .mcp.json automatically for any session opened inside that directory — no claude mcp add call needed. The interactive installer below can write this file for you.

Codex CLI

Add this entry to ~/.codex/config.toml:

[mcp_servers.formulon]
command = "npx"
args = ["-y", "@libraz/formulon-mcp"]

Restart codex and the server will appear in tool discovery.

Claude Desktop

Add formulon to claude_desktop_config.json (location depends on OS):

OS	Path
macOS	~/Library/Application Support/Claude/claude_desktop_config.json
Windows	%APPDATA%\Claude\claude_desktop_config.json
Linux	~/.config/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "formulon": {
      "command": "npx",
      "args": ["-y", "@libraz/formulon-mcp"]
    }
  }
}

Restart Claude Desktop. The tools will be available in the next session.

Interactive setup

Instead of hand-editing config files, the package ships an installer that registers (or removes) formulon across one or more clients:

npx -y @libraz/formulon-mcp init

It prompts for one or more targets, comma-separated:

1. Claude Code — user (~/.claude.json)
2. Claude Code — project (./.mcp.json)
3. Codex CLI (~/.codex/config.toml)
4. Claude Desktop (path per OS, see above)

It previews what each file will change (new / merge / replace an existing formulon entry) before writing, and never touches other servers already registered in the same file. Restart the client afterward to pick up the change.

To remove the entry later:

npx -y @libraz/formulon-mcp uninstall

Same target menu; each target is left untouched if it has no formulon entry to remove.

Other stdio MCP clients

Any stdio-capable MCP client works. Point it at:

npx -y @libraz/formulon-mcp

Or, after a global install:

npm install -g @libraz/formulon-mcp
formulon-mcp

Glossary: stdio MCP server

A long-running child process that speaks JSON-RPC over stdin / stdout. The client owns process lifetime; killing the parent terminates the server. No port is opened.

From source

For development or to pin a specific fork:

git clone https://github.com/libraz/formulon-mcp.git
cd formulon-mcp
yarn install
yarn run build

Register the absolute path to the built dist/index.js:

claude mcp add --scope user formulon node /absolute/path/to/formulon-mcp/dist/index.js

Or install the latest main without a local clone:

npx -y github:libraz/formulon-mcp

Verifying the install

Inside any connected client, the model has access to:

• formulon_version — returns the loaded Formulon engine version.
• formulon_eval_formula — evaluates one Excel formula in a throwaway workbook.

Calling either is a low-cost smoke test.

Read next

• Workflow — the open / mutate / recalc / save loop.
• Tools — every tool, grouped by category.
• Security model — what the server is allowed to do.