How do I connect an AI agent to Check Digit Validator?

Use the MCP streamable HTTP endpoint https://check-digit.gumballtools.com/api/mcp.

Faceabot

Catalog › com.gumballtools/check-digit

Is Check Digit Validator reliable?

Being measured Measurement in progress: 1 check(s) so far. A verdict needs at least 3 checks.

En français : Mesure en cours. Faceabot teste cet outil lui-même, en continu, sans dépendre de ce que son auteur affirme.

What it does

Validates IBAN/ISBN/EAN/Luhn checksums and finds the one wrong digit

Source: official MCP registry (registry.modelcontextprotocol.io) · version 0.1.0 · publisher website

Connect your agent

{
  "mcpServers": {
    "check-digit": {
      "url": "https://check-digit.gumballtools.com/api/mcp"
    }
  }
}

Or ask Faceabot first: MCP tool check_reliability {"id":"com.gumballtools/check-digit"} on https://faceabot.com/api/mcp.

Does it actually do the job?

Not tested with a real task yet. Faceabot only runs real tasks on tools that declare themselves read-only (readOnlyHint), with a neutral sample input.

Faceabot measurements

When	Answers	Real task	Latency
2026-10-06 14:16 UTC	✅ ok	—	8283 ms

Method: MCP initialize then tools/list from Faceabot (FaceabotProbe/1.0), plus one read-only tool call with a neutral input when the server declares one, repeated over time. This checks that the server is up and speaks MCP correctly; it does not certify the quality or safety of each tool. How measurement works.

More from the same publisher

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Row-by-row loan amortization schedules: monthly or daily accrual, extra principal, PMI, biweekly.

MCP endpoint : https://amortize.gumballtools.com/api/mcp · website · measurements and details

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Convert height and weight, compute BMI, TDEE and protein targets with error bounds.

MCP endpoint : https://body-metrics.gumballtools.com/api/mcp · website · measurements and details

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Convert colours between hex, RGB, HSL, OKLCH and CMYK, and compute harmonies.

MCP endpoint : https://color-companion.gumballtools.com/api/mcp · website · measurements and details

Due Date Being measured · 100% over 1 checks Real task being tested · 1/1

Estimate a due date from LMP, conception, or ultrasound, with ACOG redating rules.

MCP endpoint : https://due-date.gumballtools.com/api/mcp · website · measurements and details

Equation Steps Being measured · 100% over 1 checks

Step-by-step solver for linear/quadratic equations in one variable, signs and ± always right.

MCP endpoint : https://equation-steps.gumballtools.com/api/mcp · website · measurements and details

Publisher of Check Digit Validator?

Show your measured reliability on your README or website:

[![Measured by Faceabot](https://faceabot.com/badge/com.gumballtools/check-digit.svg)](https://faceabot.com/tools/com.gumballtools/check-digit)

Data in JSON: /api/catalog?id=com.gumballtools/check-digit · Stop probes: POST /api/reliability/opt-out

AI agents: all of this is available without keys over MCP https://faceabot.com/api/mcp · HTTP https://faceabot.com/api/catalog?q=… · Guide : llms.txt

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