Jarroba Tools · Calculation

Name: Jarroba Tools · Calculation
Author: Invarato

by Invaratoversion 0.3.0i★ –iRuns on your computer

Registry nameio.github.Invarato/jarroba-tools-calc

Install

Overview

Description from the maker (original English)

Maths a model gets wrong: units with dimensional checking, equations, sheets. 5 tools, local.

PopNx MCP’s three pillars

These three are never merged into one score: opinions, measurements and popularity are different things.

User voiceiNo reviews yetReviews open together with accounts in a later step
Our basic checksi1 of 1 passedChecked from public information; code not scanned yet
UsageiVery new↓ 87/wk · ★ –

What you can do with it

We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.

Connection: Runs on your computer
Transport: stdio
Category: Other

Install

Pick the AI app you use, then copy the settings.

Before you install

Basic checks: 1 of 1 passed
Runs on your computer with your user’s permissions (files, network, apps).
You fill in yourself: JARROBA_MCP_DOMAINS

You need

npmNode.js installed (for the npx command)

Which app do you use?

ClaudeClaude CodeCursorVS CodeChatGPT

Pick your app above. We remember it, so next time the button says “Install in …”.

Open Claude Desktop → Settings → Developer → Edit Config, and paste this into claude_desktop_config.json

{
  "mcpServers": {
    "jarroba-tools-calc": {
      "command": "npx",
      "args": [
        "-y",
        "@jarroba/mcp-calc"
      ],
      "env": {
        "JARROBA_MCP_DOMAINS": "your-value"
      }
    }
  }
}

Run this in your terminal

claude mcp add jarroba-tools-calc --env JARROBA_MCP_DOMAINS=your-value -- npx -y @jarroba/mcp-calc

Fill in the empty values before running it.

Open in Cursor

Or copy the settings yourself

Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json

{
  "mcpServers": {
    "jarroba-tools-calc": {
      "command": "npx",
      "args": [
        "-y",
        "@jarroba/mcp-calc"
      ],
      "env": {
        "JARROBA_MCP_DOMAINS": "your-value"
      }
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

Open in VS Code

Or copy the settings yourself

Paste into .vscode/mcp.json in your project

{
  "servers": {
    "jarroba-tools-calc": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "@jarroba/mcp-calc"
      ],
      "env": {
        "JARROBA_MCP_DOMAINS": "your-value"
      }
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

This one runs on your computer, and ChatGPT can only connect to servers on the internet. Pick another app.

Your choice stays on this device in a cookie; no account needed.

Values you fill in

JARROBA_MCP_DOMAINS env
Which tool domains to publish, comma-separated. Defaults to what this package is for. Valid: core, calc, diagram, kg, db, ai, logs, queue, project, tests, api, chip, chem, access, archsim, security,…

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

What it can do

Runs on your computer; the tool list appears in your AI app after you install it.

Basic checksi

We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 8, 2026

✓ Pass
Maker matches the repo
The registry name was verified with the GitHub account Invarato, which owns the repo
… Not checked yet
Still maintained
We have not read this repo from GitHub yet
… Not checked yet
Has a licence
We have not read this repo from GitHub yet
– Not applicable
Endpoint responds
This one runs on your computer; there is no internet endpoint
– Not applicable
Sign-in with OAuth
Runs on your computer and uses local settings instead
… Not checked yet
No hidden instructions in tool descriptions
Runs on your computer; we can only read tool lists from internet endpoints

Compared with others in Otheri

More stars than 0% of the other 18444 servers in this category
Published to the registry more recently than 76% of the other 18444 servers in this category
Basic checks equal to or better than 100% of the other 18444 servers in this category

Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.

Common questions

Is Jarroba Tools · Calculation safe?

It passed 1 of 1 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.

What keys or codes does it need?

The registry does not list a required key, though some servers ask you to sign in on first use.

Does it run on my computer or in the cloud?

It runs on your computer. Your AI app starts it when needed, and data does not pass through the maker’s servers (unless it calls an online service itself).

Is it still maintained?

The GitHub repo last changed –, and the latest version (0.3.0) reached the registry 12 days ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. You also need Node.js on your computer.

What can I use instead?

In the same category: Spec Driven Development, Remote Desktop Commander, Tethered Trust

Alternatives

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Tethered Trust

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README from the maker

Open the README

Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.

@jarroba/mcp-calc

**An MCP server for the maths a language model gets wrong — and, above all, for the ones it gets wrong *silently*.**

claude mcp add jarroba-calc -- npx -y @jarroba/mcp-calc

// Claude Desktop, Cursor, Cline, VS Code…

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

5 tools · ~1.6k tokens of context · stdio, runs on your machine · nothing is uploaded, no API key.

Why this exists

A model that gets 17 * 23 wrong is not the problem: that one is easy to catch. The problem is the answer that looks right.

`5 km + 300 m`. Not a hard sum — but is the answer 305, 5.3, or 5300? A dimensional slip produces a number, not an error, and the number travels into the next formula.
`x^3 - 1 = 0`. «x = 1» is *true*, and it is also only a third of the answer. A tool that stops there and says nothing teaches the caller that there was nothing else.
**9.8 m/s^2 * t^2 / 2.** Here m, s and t are all names of units *and* perfectly ordinary variable names. Read them wrong and you get a plausible quantity in the wrong dimension.

So every tool here reports how sure it is, not just what it found: exact or approximate, over which interval it searched, how many complex roots it is not showing, and which names it read as units. The one thing none of them will do is fill a gap with something plausible.

The tools


`calc_eval`	Arithmetic with units and dimensional checking: `100 km/h to m/s`, `5 km + 300 m`, `70 kg to lbs`, `det([[1,2],[3,4]])`. Adding metres to kilos is an error, not a silent number. Flags results that are not finite (NaN, ±∞), and says which names it read as units
`calc_solve`	One equation (`x^2 - 5x + 6 = 0`, `sin(x) = 0.5`) or a linear system, one equation per line. Says whether the answer is exact or approximate, over which interval it searched, the degree of the polynomial and how many complex roots are not shown. Never invents a root it did not find
`calc_sheet`	A multi-line calculation sheet with the result of every line. Variables carry downwards, units travel with the value, `#` starts a comment, `ans` is the previous result, and an error stays on its own line instead of killing the sheet. Declare currencies with `# @moneda USD = 1.08 EUR` — you supply the rate, so the sheet still computes the same thing next year. Optional Markdown table out
`calc_derive`	Exact symbolic derivatives that keep the units: `d/dx (3 m * x)` is `3 m`, not `3`. Higher orders, and can evaluate the result at a point. Refuses to answer «0» when the variable is not in the expression, because a correct zero for the wrong question is the worst answer there is
`calc_steps`	The worked steps, verified: a linear or quadratic equation, a derivative (naming the rule), or Gaussian elimination row by row. When it cannot explain a case it returns `covered: false` instead of writing a plausible derivation — which is the point, if a person is going to read it

What it will not do

No symbolic simplification. It was the obvious sixth tool and it was dropped after measuring: the engine leaves (x+1)^2 - (x-1)^2 untouched (it is 4x) and does not know sin²+cos²=1. A tool that hands back your own input under the label *"simplified"* is worse than no tool, because the caller cannot tell «already simplest» from «I could not do it».
No integrals, no limits, no inequalities. Not supported, and said so here rather than discovered at the wrong moment.
Steps beyond degree 2 for equations. calc_solve still answers exactly; what is missing is the explanation, and calc_steps says which cases it covers in every response.

Where it comes from

The engine is the same code that runs the calculator at jarroba.com/tools — pure TypeScript, ~200 unit tests, no server. This package is the whole catalogue filtered down to the calculation domain; if you want the other 95 tools (logs, tests, SQL, SPARQL, diagrams…), install @jarroba/mcp instead. You can also widen this one without switching packages: JARROBA_MCP_DOMAINS=calc,core.

MIT. Nothing here talks to the network. Source: github.com/Invarato/jarroba-mcp.

Jarroba Tools · Calculation

Overview

PopNx MCP’s three pillars

What you can do with it

Install

Before you install

Values you fill in

What it can do

Basic checksi

Maker matches the repo

Still maintained

Has a licence

Endpoint responds

Sign-in with OAuth

No hidden instructions in tool descriptions

Compared with others in Otheri

Common questions

Alternatives

Spec Driven Development

Remote Desktop Commander

Tethered Trust

README from the maker

@jarroba/mcp-calc

Why this exists

The tools

What it will not do

Where it comes from