Onto MCP Server

by ravixalgorithm Your server? Claim it

answering

Onto is answering right now. Last checked 6 min ago. 87 installs a week from npm. Last commit 5 Sep 2026.

Clean Markdown and AI-readability scoring for any URL. Built for AI agents.

Installs per day peak 284 · avg 21 · +56% w/w

a month agotoday

Uptime history 14 days of history · worst day 98%

14 days agonow

100.0%

Uptime 24h

92 of 92 checks

—

Tools

hidden behind auth

514 ms

Response time

average over 24h

Installs / week

npm and PyPI

Onto missed 2 checks this week

Everything else answered, so this is steady rather than shaky. We check every 15 minutes, which is how a one-off gets told apart from the start of a pattern, and how you hear about the next one within the hour instead of from your users.

Connect this server

Endpoint below is the one we actually reach during checks — not the one copied from a README. Last verified 6 min ago.

Claude Code Claude Desktop Codex Cursor VS Code

run in your terminal

claude mcp add onto --transport http https://api.buildonto.dev/mcp

~/Library/Application Support/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "onto": {
      "url": "https://api.buildonto.dev/mcp"
    }
  }
}

~/.codex/config.toml

[mcp_servers.onto]
url = "https://api.buildonto.dev/mcp"

.cursor/mcp.json

{
  "mcpServers": {
    "onto": {
      "url": "https://api.buildonto.dev/mcp"
    }
  }
}

.vscode/mcp.json

{
  "mcpServers": {
    "onto": {
      "url": "https://api.buildonto.dev/mcp"
    }
  }
}

This one needs environment variables set before it will start: ONTO_API_KEY (Your Onto API key (get one at https://app.buildonto.dev/read/keys — free tier includes 1,000 credits/month).), ONTO_API_BASE (Optional override for the Onto API base URL. Defaults to https://api.buildonto.dev.). The author declared them in the registry entry; get the values from the project itself.

This endpoint answered with an authorization challenge. The server is running, and it signs you in through your browser: there is no API key to paste.

Endpoints

URL	Transport	State	Latency	Checked
https://api.buildonto.dev/mcp	streamable-http	sign-in	225 ms	6 min ago

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Onto — questions

Answers built from our own checks of this server.

Why is there no tool list for Onto?

The server answered our handshake with an authorization challenge, so it is running — but it will not describe its tools to an anonymous client. To see them you need to connect with your own credentials. We record it as alive, not as broken: 100.0% of checks in the last 24 hours got a reply.

Is Onto working right now?

We send a real MCP handshake every 15 minutes. Over the last 24 hours 92 of 92 checks got a reply (100.0%), average response time 514 ms. The bar chart above shows every period we have measured.

How do I connect Onto?

Copy the ready config from this page — we generate it for Claude Code, Claude Desktop, Codex, Cursor and VS Code, each with the file path that client actually reads. It is a remote server, so there is nothing to install — the client connects to the address. You sign in through your browser once and the client keeps the session: no key to copy, and it refuses anonymous clients.

How do you sign in to Onto?

No API key is involved. Onto answers our knock with an OAuth challenge, so you authorise it once in your browser and the client keeps the session. That is also why we see no tool list: it will not describe itself to an anonymous client, and that is the server working as intended, not a fault.

How fast is Onto?

It answers our handshake in 514 ms on average, which is faster than 28% of all working MCP servers we measure. The comparison comes from our own checks across the whole registry, every 15 minutes.

How many people use Onto?

The npm package @ontosdk/mcp was installed 87 times in the last week. Week over week that is +56%. We show installs rather than GitHub stars on purpose: a star is a bookmark, an install is someone actually running it.

Is Onto open source?

Yes — it is published under the MIT licence, written in TypeScript and 1 stars on GitHub. The source link is on this page, so you can read exactly what it does with your data before you connect it.