truecalc-mcp

Registered with the MCP Registry via mcp-name: io.github.truecalc/truecalc-mcp.

MCP server that exposes truecalc spreadsheet formula evaluation as tools for AI assistants.

A comprehensive spreadsheet function library (see the live count above) — evaluate, validate, and explain formulas without writing any code. Ground-truth conformance against real Google Sheets. Backed by the same engine used in the Rust crate and npm package.

// Tool: evaluate
{ "formula": "SUM(A1, B1)", "variables": { "A1": 100, "B1": 200 } }
// => { "value": 300, "type": "number" }

Install

npx (no install step)

npx -y @truecalc/mcp

Resolves the prebuilt truecalc-mcp binary for your OS/CPU via @truecalc/mcp — same Rust binary as the crate below, no Rust toolchain required.

cargo

cargo install truecalc-mcp --force

Claude Desktop setup

Add the server to ~/Library/Application Support/Claude/claude_desktop_config.json:

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

Using a cargo installed binary instead:

{
  "mcpServers": {
    "truecalc": {
      "command": "/Users/your-username/.cargo/bin/truecalc-mcp"
    }
  }
}

Restart Claude Desktop. The tools will appear automatically.

Tools

evaluate

Evaluate a formula with optional variable bindings.

{ "formula": "SUM(A1, B1)", "variables": { "A1": 100, "B1": 200 } }

Returns: { "value": 300, "type": "number" }

validate

Check whether a formula parses without errors.

{ "formula": "IF(score >= 60, \"pass\", \"fail\")" }

Returns: { "valid": true } or { "valid": false, "error": "..." }

explain

Describe a formula and list the functions it uses.

{ "formula": "IF(AND(A1 > 0, B1 > 0), SUM(A1, B1), 0)" }

Returns: { "description": "Formula using: AND, IF, SUM", "functions_used": ["AND", "IF", "SUM"] }

batch_evaluate

Evaluate multiple formulas sharing the same variable bindings.

{
  "formulas": ["SUM(A1, B1)", "AVERAGE(A1, B1)", "MAX(A1, B1)"],
  "variables": { "A1": 10, "B1": 90 }
}

Returns an array of results in the same order.

list_functions

Return the full catalogue of supported spreadsheet functions with category, syntax, and description.

Supported functions

Covers math, logical, text, financial, and statistical categories. For the full list with signatures and descriptions, call the list_functions tool — it returns the live registry.

Related

• truecalc-core — the underlying formula engine (Rust library)
• @truecalc/core — WebAssembly package for JavaScript/TypeScript
• @truecalc/mcp — this server, published to npm for npx

Documentation

docs.truecalc.app

License

MIT