QAmcp

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Directory / Klarbon

Klarbon

Q: Is Klarbon MCP server safe?

QAmcp's test on 10 Nov 2026: None of the hidden-instruction wordings we know were found in its 6 tool descriptions. Its error messages showed no secrets or internal details. 4 of its 6 tools are labeled read-only; the others may change or send things. Overall it scored 88/100 on 10 Nov 2026. A test can only see what the server shows from outside, not what it does with your data behind the scenes. Connect servers from makers you trust.

by klarbon.app · https://klarbon.app/mcp

Open, check and convert European e-invoices and bank statements. No document archive.

6 tools✓ no account neededPricing: on their site

See pricing →Visit website

88 /100

PASS · WITH NOTES

11 of 11 checks · 10 Nov 2026

Test it now for current results

At a glance

Runs where: On their server. What you send to it goes to them.
What you need: Nothing: it answered without a login
Tools: 6 tools
Its own safety labels: 4 read-only, 2 labeled as changing things
Memory it takes: About 2,200 tokens of your AI's memory, just for its tool descriptions
Largest answer: About 38.3 KB in our test
Speed: Average answer in our test: 279 ms

Tokens are an estimate: the characters in its tool names, descriptions and inputs, divided by 4. The exact number depends on your AI model. Safety labels are what the server says about itself. From our latest test, 10 Nov 2026.

Is Klarbon MCP server safe?

None of the hidden-instruction wordings we know were found in its 6 tool descriptions.
Its error messages showed no secrets or internal details.
4 of its 6 tools are labeled read-only; the others may change or send things.
Overall it scored 88/100 on 10 Nov 2026.

A test can only see what the server shows from outside, not what it does with your data behind the scenes. Connect servers from makers you trust.

What this test does not check

Its source code and packages.
What a tool quietly does behind the scenes, such as writing a file or calling another service.
Instructions hidden inside live tool answers. We only look for those in tool descriptions.
Hidden instructions worded in a way our list doesn't know yet.
Tools that could change something. Those are read, never run.

What QAmcp can and can't see · How to tell if an MCP server is safe · Hidden instructions · Prompt injection

Known security advisories

It lists no public code, so there is nothing to look up in GitHub Security Advisories or OSV.dev. QAmcp tests how a server behaves. It does not scan source code.

What it can do

6 tools, in the server's own words.

list_formatsread-only

Lists every e-invoice and bank statement format Klarbon handles, with what each can do now: open, check, convert from, convert to, make.

open_invoiceread-only

Reads an e-invoice (XRechnung, ZUGFeRD, Factur-X, Peppol BIS, UBL, CII and more) into structured data: parties, lines, totals, VAT, payment details.

check_invoiceread-only

Validates an e-invoice against EN 16931 and its national rules (XRechnung, Peppol BIS and others), with each finding explained in plain words and how to fix it.

convert_invoice

Converts an e-invoice to another format (for example UBL to XRechnung, or CII to a Factur-X PDF) and validates the result; only a valid file is returned.

convert_bank_statement

Converts a bank statement file (CAMT.053, MT940, CODA, Norma 43, CFONB 120, BAI2, OFX, QIF and more) to another format such as CAMT.053, MT940, CSV or Excel, a…

check_vat_numbersread-only

Checks up to 25 EU VAT numbers (and Northern Ireland's XI numbers) in the European Commission's VIES service: valid or not valid now, with the registered name …

Test results

Safe mode: only tools labeled read-only were run. How the test works

!
Ready for the newest MCP version
1 warning
- !Uses an older MCP version (2025-06-18). It works today, but it isn't on the July 2026 version (2026-07-28) yet.
note
!
Every tool is described
1 warning
- !convert_bank_statement: Inputs with no description: opening_balance, date_order, century, currency, decimal_separator, account
note
✓
ConnectsConnected in 919 ms
pass
✓
Lists its toolsFound 6 tools
pass
✓
Tools are labeled safe or dangerousEvery tool has a safety label
pass
✓
No known hidden instructionsNone of the hidden-instruction wordings we know were found in tool descriptions. New wordings can get past this check.
pass
✓
Tools work with good inputs
All good
- ✓list_formats: Worked (284 ms)
- ✓check_invoice: Answered with an error, probably because of our sample input: This call needs an API key: send it in the Authorization header as Bearer followed by the key. {"ok":false,"error":"auth","message":"This c…
- ✓check_vat_numbers: Worked (313 ms)
- –open_invoice: Not run: labeled read-only, but its name starts with "open", which usually means it changes something. Skipped to be safe: if it only reads, a clearer name helps AI apps too, or test again with --owner
- –convert_invoice: Not run: labeled as changing data
- –convert_bank_statement: Not run: labeled as changing data
pass
✓
Bad inputs give a clean error
All good
- ✓check_invoice: Refused wrong type for "file_base64" with a clear error
- ✓check_vat_numbers: Refused missing required input "numbers" with a clear error
- –check_vat_numbers: The server limited our requests, so bad inputs were not tested
pass
✓
Fast enough
All good
- ✓Connecting took 919 ms
- ✓Listing tools took 274 ms
- ✓Average tool answer: 279 ms
- ✓check_vat_numbers: Slowest tool: check_vat_numbers (313 ms)
pass
✓
No secrets leakedChecked 4 error messages: no secrets or internal details
pass
✓
Follows MCP best practices (not scored yet)Tool names, safety labels and tool list size follow the MCP guide
pass
–
Tools work togetherNo tool's answer could be fed into another tool, so there were no chains to test (not counted either way)
not tested

Test it yourself

Free and open source. Same checks, same score.

npx qamcp-cli https://klarbon.app/mcp

Show this score on GitHub

Free for every server in the directory. Paste this into your README: the badge shows the score from our latest test.

[![QAmcp score](https://qamcp.dev/s/app-klarbon-klarbon.svg)](https://qamcp.dev/s/app-klarbon-klarbon.html)

Score over time

10 Nov 202688

One test so far. New tests will show here.

Reviews

Coming soon: reviews from people who use Klarbon, signed in with GitHub, one per person. Reviews never change the score.

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