Onto MCP server

Onto MCP Server

The official Onto Model Context Protocol server. Add clean web content reading and AI-readability scoring to Claude Code, Cursor, Cline, Zed, or any MCP-compatible AI client.

What this does

Onto's MCP server exposes these tools to any AI agent:

• readurl** — Read any URL and get back clean, agent-ready Markdown (typically 10× smaller than raw HTML)
• scoreurl** — Get the AIO (AI-readability) score for any URL with a breakdown of what helps and what hurts AI consumption
• readandscore — Both at once: clean content plus quality assessment so the agent knows how much to trust the source
• batch — Read, score, or extract many URLs (an explicit list or a whole site) in one call
• mapsite** — Discover a site's URLs via its sitemap, without reading them
• extractdata** — Return the structured data a page already declares (JSON-LD, OpenGraph, meta)

Every tool response ends with a one-line ⚡ Onto report — reduction, tokens saved, and AIO score — so the value is visible on every call.

This is the official MCP wrapper for the Onto Read API. It's a thin, deterministic layer: Onto cleans and scores with a rule-based engine (no LLM in the loop), so your agent's own model never has to parse raw HTML.

Why use this?

When AI agents read websites today, they parse hundreds of KB of React noise to find a few KB of actual content. This burns tokens and causes hallucinations.

Onto strips the noise server-side, returns the agent-ready format, and reports a confidence score for the source. One tool call, one accurate answer.

Quick start

1. Get an Onto API key

Sign up at app.buildonto.dev and create an API key at Read → Keys.

Free tier: 1,000 credits / month. No credit card.

2. Install in Claude Code

Add to your Claude Code MCP config:

{
  "mcpServers": {
    "onto": {
      "command": "npx",
      "args": ["-y", "@ontosdk/mcp@latest"],
      "env": {
        "ONTO_API_KEY": "onto_sk_live_your_key_here"
      }
    }
  }
}

Restart Claude Code. The Onto tools (readurl, scoreurl, readandscore, batch, mapsite, extractdata) will appear in the available tools list.

3. Install in Cursor

Add the Onto server to ~/.cursor/mcp.json (all projects) or .cursor/mcp.json (this repo). Or use the UI: Customize (sidebar) → MCPs → add a custom server, same JSON.

{
  "mcpServers": {
    "onto": {
      "command": "npx",
      "args": ["-y", "@ontosdk/mcp@latest"],
      "env": {
        "ONTO_API_KEY": "onto_sk_live_your_key_here"
      }
    }
  }
}

Fully quit Cursor (Cmd+Q / Ctrl+Q) and reopen.

See examples/ for Cline, Zed, and Continue configs.

4. Use it

In Claude Code or Cursor, try:

Read https://stripe.com/pricing using Onto and summarize the pricing tiers.

The agent calls read_url, gets clean Markdown, and returns an accurate summary without parsing hundreds of KB of layout HTML.

Tools

read_url

Returns clean Markdown for a URL with metadata about the extraction (sizes, reduction %, cache state).

Input:

score_url

Returns the AIO (AI-readability) score for a URL — 0-100 with a letter grade, hallucination risk, and a structured list of penalties / benefits / recommendations.

Input:

readandscore

Returns clean Markdown plus the AIO score in one call. Recommended default for agentic workflows.

Input: same as read_url.

batch

Shortened. The full README is on GitHub.