Jarroba Tools · Calculation
NPM · @JARROBA/MCP-CALC · SCANNED SEP 26
Maths a model gets wrong: units with dimensional checking, equations, sheets. 5 tools, local.
Available components
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. How we score → Why this is hard to score →
Supply Chain Security98
- No malware found by supply-chain analysis.Pass
- No known CVEs affecting this package version or its production dependencies.Pass
- No install/post-install scripts declared.Pass
- 35 of 106 dependencies flagged as unhealthy. View diagnostics → Partial
Provenance & Transparency19
- Repository check failed: the declared repository URL returned HTTP 404. See how to fix → View diagnostics → Fail
- Provenance check failed: no build-provenance attestation is published. See how to fix → View diagnostics → Fail
- Clear OSI-approved license (MIT).Pass
- Actively maintained (last published 9 days ago).Pass
- Security-disclosure policy not yet verified: we couldn't inspect the source repository.Unverified
Schema Quality & AI Usability67
- AI-judged instruction clarity (good).Pass
- Context-footprint check failed: tool/resource definitions use about 808 tokens (~161/item across 5 items; 5 tools + 0 resources), over budget; trim descriptions and params. See how to fix → Fail
- Usage-examples check failed: none of the tools include examples. See how to fix → Fail
Stability & Change Management33
- Stability observed for 10 of 30 days with no destabilising changes; credit accrues until the full window elapses.Partial
Tool Coverage100
- 100% of tools have a non-trivial description (not blank, and not just the tool's name).Pass
- 100% of tool parameters carry a description.Pass
Tool Safety75
- No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.Pass
- 0 of 1 tool(s) whose name or description implies an irreversible operation declare an MCP destructiveHint annotation; "calc_eval" implies "eval" and declares readOnlyHint instead, contradicting what its own name says it does. See how to fix → Fail
- An AI judge read all 6 captured unit(s) of tool text and found none that tries to manipulate the model reading it.Pass
Capabilities100
- Implements a supported MCP spec version (2025-11-25); the latest is 2026-07-28.Pass
How do I install the Jarroba Tools · Calculation MCP server?
Jarroba Tools · Calculation runs locally as an npm package, launched with npx -y @jarroba/mcp-calc. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.
npm · @jarroba/mcp-calc
claude mcp add invarato-jarroba-tools-calc -- npx -y @jarroba/mcp-calc
{
"mcpServers": {
"invarato-jarroba-tools-calc": {
"command": "npx",
"args": [
"-y",
"@jarroba/mcp-calc"
]
}
}
} {
"servers": {
"invarato-jarroba-tools-calc": {
"command": "npx",
"args": [
"-y",
"@jarroba/mcp-calc"
]
}
}
} codex mcp add invarato-jarroba-tools-calc -- npx -y @jarroba/mcp-calc
{
"$schema": "https://opencode.ai/config.json",
"mcp": {
"invarato-jarroba-tools-calc": {
"type": "local",
"command": [
"npx",
"-y",
"@jarroba/mcp-calc"
],
"enabled": true
}
}
} openclaw mcp add invarato-jarroba-tools-calc --command npx --arg -y --arg @jarroba/mcp-calc
mcp_servers:
invarato-jarroba-tools-calc:
command: "npx"
args: ["-y", "@jarroba/mcp-calc"] {
"McpServers": {
"invarato-jarroba-tools-calc": {
"Transport": "stdio",
"Command": "npx",
"Arguments": [
"-y",
"@jarroba/mcp-calc"
]
}
}
} assistant mcp add invarato-jarroba-tools-calc -t stdio -c npx -a -y @jarroba/mcp-calc
{
"mcpServers": {
"invarato-jarroba-tools-calc": {
"command": "npx",
"args": [
"-y",
"@jarroba/mcp-calc"
]
}
}
} Every change we have recorded for this component, newest first. Security-relevant changes are always shown. ▲ marks a change for the better, ▼ a change for the worse; unmarked changes are neutral.
- 25 Sept 26 0
- We updated how we score, so this day's move reflects our rubric, not a change to the server See what changed → functional
- 24 Sept 26 +4
- Stability: unverified → 0.27 ▲ functional
- 16 Sept 26 62
First indexed and scored.
Diagnostic detail from the automated scan of this channel: what the scanner observed at each step, so you can see exactly where a check passed or failed. It is informational only and never changes the trust score.
Captured 26 Sept 2026 · Analysed npm/@jarroba/mcp-calc@0.1.4
Provenance No attestation
The registry publishes no build provenance for this version, so there is nothing to verify.
| Result | No attestation |
|---|---|
| Ecosystem | npm |
Background: How many MCP packages publish verified provenance →
Dependencies 106 packages
| Packages resolved | 106 |
|---|---|
| Stale | 35 |
| Tree resolution | Complete |
Background: SBOMs and build attestations, explained →
The tools this component advertises to a client, with an estimated token cost for each. Expand a tool to see its parameters and schema. The per-tool counts are indicative and are not scored directly; the schema's total context footprint is one signal in Schema Quality & AI Usability. A tool's description is untrusted text the model reads on every call, which is what makes this list a security surface and not just an inventory: how tool poisoning works →
calc_derive ~192
Differentiate an expression symbolically, exactly: "x^3 + 2x", "sin(x)*cos(x)", "x^x". Keeps units, so d/dx (3 m * x) is "3 m" and not 3. Can take higher-order derivatives and evaluate the result at a point. Says which name it read as a unit, and refuses to answer "0" when the variable is not in the expression.
| Name | Type | Req | Description |
|---|---|---|---|
| at | number | – | Also evaluate the derivative at this value of the variable |
| expression | string | yes | e.g. "x^3 + 2x" or "9.8 m/s^2 * t^2 / 2" |
| order | integer | – | 1 = first derivative, 2 = second… up to 4 |
| variable | string | – | Differentiate with respect to this (guessed if omitted) |
No output schema declared.
No examples provided.
calc_eval ~108
Evaluate a mathematical expression 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 incompatible units is an error, not a silent number. Also flags results that are not finite (NaN, infinity).
| Name | Type | Req | Description |
|---|---|---|---|
| expression | string | yes | e.g. "100 km/h to m/s" or "sqrt(2)^2 + 2^10" |
No output schema declared.
No examples provided.
calc_sheet ~141
Evaluate a multi-line calculation sheet and return 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". Good for checking a quote or a budget line by line.
| Name | Type | Req | Description |
|---|---|---|---|
| as_markdown | boolean | – | Also return the sheet as a Markdown table |
| sheet | string | yes | One expression per line, e.g. "width = 3.5 m height = 2.4 m area = width * height" |
No output schema declared.
No examples provided.
calc_solve ~139
Solve an equation in one unknown ("x^2 - 5x + 6 = 0", "sin(x) = 0.5") or a linear system (one equation per line). Says whether the answer is EXACT or an approximation, and over which interval it searched. Never invents a root it did not find.
| Name | Type | Req | Description |
|---|---|---|---|
| equations | string | yes | One equation, or several separated by newlines for a system |
| from | number | – | Lower bound for the numeric search |
| to | number | – | Upper bound for the numeric search |
| unknown | string | – | Which variable to solve for (guessed if omitted) |
No output schema declared.
No examples provided.
calc_steps ~165
Show the WORKED STEPS of a calculation, verified step by step: a linear or quadratic equation, a derivative (naming which rule applies), or Gaussian elimination on a linear system row by row. Each step comes with the name of the rule used. When it cannot explain a case it says so (covered: false) instead of inventing a plausible-looking derivation — useful when you have to show your work to a person.
| Name | Type | Req | Description |
|---|---|---|---|
| input | string | yes | An equation ("2x + 6 = 0"), an expression to differentiate ("sin(x)*x^2"), or one equation per line for a system |
| kind | string | – | What to explain |
| variable | string | – | The unknown or the variable to differentiate by (guessed if omitted) |
No output schema declared.
No examples provided.
What is the Jarroba Tools · Calculation MCP server?
Jarroba Tools · Calculation is an MCP server listed in the public MCP registry as io.github.Invarato/jarroba-tools-calc. Maths a model gets wrong: units with dimensional checking, equations, sheets. 5 tools, local. This page covers its npm package (@jarroba/mcp-calc).
Is the Jarroba Tools · Calculation MCP server safe to use?
Jarroba Tools · Calculation scores 66 out of 100 on VerifyMCP. We found no known CVEs affecting it as of 26 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 Jarroba Tools · Calculation MCP server expose?
Jarroba Tools · Calculation exposes 5 tools: calc_eval, calc_solve, calc_sheet, calc_derive, calc_steps. Their descriptions and schemas cost roughly 745 tokens of context every time the server is loaded.
Is the Jarroba Tools · Calculation MCP server still maintained?
Jarroba Tools · Calculation is still listed as active in the MCP registry. We last reached this channel on 26 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 Jarroba Tools · Calculation MCP server under?
Jarroba Tools · Calculation declares the MIT licence, which is OSI-approved. That covers the source only, and says nothing about the cost of any service it calls.