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    Free Tool Page Builder: Calculator and Converter Pages

    1

    Turn a spec.json into one self-contained calculator or converter page with explanation and FAQ. The formula is allowlisted, never eval'd, and a checker re-reads the page against its spec.

    $5

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    Free Tool Page Builder: Calculator and Converter Pages

    Free Tool Page Builder: Calculator and Converter Pages

    Example session with this skill installed

    Build me a tip calculator page from this spec.json, then check the page before I publish it on my static site.

    • Read your context and instructions
    • Compiled the free tool page

    Summary

    The agent built one self-contained HTML page from the example spec and ran the page checker on it: 8 of 8 checks pass. As a control it also ran the checker on an unrelated page, which fails 6 of 8 checks, so the checker does not pass pages that were not built from the spec.

    $ python3 scripts/build_page.py assets/example-spec.json tip.html
Built: tip.html

$ python3 scripts/page_check.py tip.html assets/example-spec.json
  PASS  title
  PASS  h1
  PASS  description
  PASS  formula
  PASS  faq
  PASS  placeholder
  PASS  explanation
  PASS  ext-script
PAGE-CHECK pass=8 fix=0

$ python3 scripts/page_check.py other.html assets/example-spec.json   # a page not built from this spec
  FIX   title: got 'Cold cure'
  FIX   h1: got 'The tool cures the common cold in the cloud'
  FIX   description: no <meta name='description'>
  FIX   formula: JS formula '_pyRound(_f(_f(bill * tip_pct) / 100.0), 2.0)' not in page; missing input ids: ['bill', 'tip_pct']
  FIX   faq: found 0 <details>, need >= 2
  PASS  placeholder
  FIX   explanation: explanation has 0 words, need >= 50
  PASS  ext-script
PAGE-CHECK pass=2 fix=6
    CheckBuilt pageUnrelated page
    Title and H1passfix
    Meta descriptionpassfix
    Formula and inputspassfix
    FAQ countpassfix
    Explanation lengthpassfix
    Placeholder textpasspass
    External scriptspasspass

    Next steps

    1. Open the built page in a browser and try a few inputs, including the example from your spec.
    2. Upload the single HTML file to your static host; it loads nothing from other servers.
    3. If you change the spec, build the page again and re-run the checker before you publish.

    Connects securely to your tools. The creator never sees your data.

    About this skill

    Use when you want a free calculator or converter page for a static host without a framework, CDN or build step.

    You write spec.json (tool name, inputs, formula, explanation, FAQ, optional example); build_page.py validates the formula against an allowlist (+ - * / ** %, parentheses, min, max, round, abs; no eval or exec) and writes one HTML file with inline CSS and JS.

    The page's round() and % follow Python's rules (round half to even, remainder takes the sign of the divisor), and a step with no finite number gives no number on both sides. This was tested with a Python model of JavaScript's number rules, not in a JavaScript engine; ** (power) uses Math.pow and was not covered.

    page_check.py re-checks a page this skill built against its spec in eight checks: title, H1, meta description, formula code and one input per spec input, example result in Python, FAQ count, explanation length, placeholder text, and no external script or import from a URL. Thresholds are heuristics.

    Do not use when you need server logic, live data, or a check of whether the formula is right for your use case.

    Requires: Python 3.9+ (standard library only). The generated page needs a browser from 2018 or later.

    Independent: Not affiliated with or endorsed by any search engine, advertising platform, or Anthropic.

    Formulas only with + - * / ** %, parentheses, min, max, round, abs; round(x, n) needs n as a whole number from 0 to 15. page_check reads the page's text and does not run its JavaScript; pages built by other tools get FIX on the formula and explanation checks. No legal, SEO-ranking or platform-approval check.

    How to use

    1. 1

      Connect your agent to the Agensi MCP

      Copy the prompt and paste it into Claude, ChatGPT, Cursor or any agent that supports MCP. It sets up the connection for you. Manual setup

    2. 2

      Sign in to Agensi

      Your agent shows a sign-in link. Sign in and click Allow.

    3. 3

      Ask for what you need

      Your agent loads this skill and uses it on your task. It always asks before any payment.

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    Checked by our 8-point scan before listing

    Fresh listing

    Recently published to Agensi

    Money-back guarantee

    Doesn't do what its page promises? You get your money back.

    Trust & safety

    Security scan

    Security scan passed 5 days ago

    Requires

    Python 3.9+
    Python

    Permissions

    Terminal / Shell
    Read Files
    Write Files
    Listed5 days ago

    What's inside

    Frequently Asked Questions

    No. One HTML file with inline CSS and JS; it needs a browser from 2018 or later.

    No. It is parsed against an allowlist and translated to JavaScript at build time.

    For round() and % they follow Python's rules, tested with a Python model of JavaScript's number rules (14 formulas × 300 inputs plus ties like round(2.675, 2)). ** was not tested.

    No. It checks that the example inputs give the expected result, not that the formula fits your use case.