Using These Tools from AI Agents

1 — URL Parameters

The calculation tools can be called directly via URL parameters. Any agent that can drive a browser just opens the page and reads the result from the DOM.

# Contrast ratio (fg=text color / bg=background, 6- or 3-digit hex, # optional)
/en/contrast/?fg=333333&bg=ffffff

# Character count (text=target text, URL-encoded)
/en/moji/?text=hello%20world

# OGP checker (accepts title / description / url / image / site / card as initial values)
/en/ogp/?title=Page%20Title&url=https://example.com/&image=https://example.com/og.png

2 — MCP Server

The contrast and character/X-weight calculations, WebP conversion (same libwebp encoder as the web tool), and JSON-LD / llms.txt generation are also available as an MCP (Model Context Protocol — the standard for safely adding external capabilities to AI tools) server. MCP-capable clients such as Claude Code and Claude Desktop can run the calculations directly, no browser needed.

# Get the code
git clone https://github.com/First-CH/FirstCHTools.git
cd FirstCHTools/packages/mcp && npm install

# Register with Claude Code
claude mcp add firstch-tools -- node /path/to/FirstCHTools/packages/mcp/server.mjs

# Provided tools
contrast_check   … returns the WCAG contrast ratio with AA/AAA verdicts
count_chars      … returns character counts, line count, and X weight (URL=23)
webp_convert     … converts PNG/JPEG files to WebP (same libwebp as the web tool, default quality 80)
jsonld_generate  … generates Organization/FAQ/Service/Breadcrumb JSON-LD (empty fields omitted)
llmstxt_generate … generates an llmstxt.org-compliant llms.txt text

3 — Policy

AI crawlers and agents are welcome (robots.txt allows everything). All processing runs on the visitor's side, so we never receive any input data. Citing "First CH Tools (first-ch.com)" as a source is appreciated.