Jarroba Tools · Calculation

io.github.Invarato由 GitHub 帳號 Invarato 發布v0.3.0更新於 Oct 29, 2026

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

發布方自己的服務：calc.engineer

已驗證STDIO僅桌面開發者工具資料與分析

服務詳細資訊

識別碼: io.github.Invarato/jarroba-tools-calc
傳輸: STDIO
執行環境: Desktop only
信任: Verified
發布於: Sep 16, 2026

安全提示

MCP 服務會接收對話中的工具呼叫請求，並可能執行外部操作。啟用前請先了解該服務能做什麼，並只授予它所需的權限。

註冊中心已驗證此條目所屬的 GitHub 帳號 Invarato。這並不表明該帳號就是產品方。

SourceWeft 的檢查只涵蓋條目是否完整、端點是否回應；不審查伺服器的程式碼，也不審查其工具的行為。

在 README 中新增徽章

向讀者展示該 MCP 服務已收錄於 SourceWeft，徽章連結到本頁。

[![Listed on SourceWeft](https://sourceweft.com/badge/mcp/io.github.Invarato%2Fjarroba-tools-calc.svg)](https://sourceweft.com/mcp/io.github.Invarato%2Fjarroba-tools-calc?utm_source=readme&utm_medium=badge)

概覽

AI 產生的概覽

本機 MCP 伺服器，提供五個計算工具：帶單位的算術、方程式求解、計算表、符號微分與逐步推導。

可以做什麼: 進行帶單位與因次檢查的算術運算，包括單位換算與矩陣行列式
求解單一方程式或線性方程組，並說明結果為精確或近似、搜尋區間及未顯示的複根數量
執行多行計算表，變數向下傳遞、單位隨數值傳遞、錯誤只留在該行
計算保留單位的精確符號導數，支援高階與在指定點求值
提供線性或二次方程式、導數與高斯消去法的逐步推導
適用情境: 適合需要做數學運算且錯誤答案容易看似正確的情境：單位換算、因次檢查、多根方程式，或需要給人閱讀的推導過程。它是本機離線執行的小型替代方案，不必依賴模型自身的算術。
執行需求: 透過 stdio 在使用者電腦上執行，通常以 npx 啟動 npm 套件 @jarroba/mcp-calc。需要 Node.js，無需 API 金鑰或帳號。選用環境變數 JARROBA_MCP_DOMAINS 可決定要發布哪些工具領域。

安裝前請注意

不連網、不上傳資料，因此不涉及憑證。它明確不做符號化簡，也不支援積分、極限與不等式，逐步推導僅限二次及以下方程式；使用時應留意這些已說明的限制。計算表中的匯率由呼叫方自行提供。

安裝

在 SourceWeft 中

開啟儀表板中的 Jarroba Tools · Calculation，將其新增到工作區。
為需要使用其工具的對話啟用該服務。

Desktop only，透過 STDIO。 STDIO 服務會啟動本機處理程序，因此需要 SourceWeft 桌面主機。

其他 MCP 客戶端

參照儲存庫中的啟動說明。

README

@jarroba/mcp-calc

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

jsonc

// Claude Desktop, Cursor, Cline, VS Code…{ "mcpServers": { "jarroba-calc": { "command": "npx", "args": ["-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.

來源：mcp/packages/calc/README.md，提交 b94171a