Remote connector (OAuth)

Connect Onto to ChatGPT, Claude, and any MCP client as a hosted connector — no API key to paste, no local install. You sign in with your Onto account once, and every tool call bills your existing plan.

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One URL: https://api.buildonto.dev/mcp. Add it as a custom connector, authorize with your Onto account, and the same six tools appear — no npx, no config file, no key in plaintext.

What is the remote connector?

The remote connector is the Onto Read API exposed as a hosted MCP server over Streamable HTTP. Where the local server (@ontosdk/mcp) runs on your machine via npx and reads an API key from an env var, the remote connector runs on Onto's infrastructure and authenticates you with OAuth — the same "Connect" flow ChatGPT and Claude use for every other integration.

It exposes the exact same six tools — read_url, score_url, read_and_score, batch, map_site, extract_data — and hits the same /v1/* endpoints, so pricing, quotas, and the AIO scoring model are identical to every other surface.

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Onto reads URLs the model already has. It's a fetch-and-score tool, not a web-search provider — perfect for surfaces that already search the web and just need clean, trustworthy content for the links they find.

The connector URL

Every client asks for one thing — the server URL. It's the same everywhere:

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https://api.buildonto.dev/mcp

You don't enter a key. The first time you connect, the client walks you through an OAuth sign-in with your Onto account and stores the resulting token itself.

Connect in Claude

Open connector settings

In Claude (claude.ai or the desktop app): Settings → Connectors → Add custom connector.

Paste the URL

Name it Onto and set the URL to https://api.buildonto.dev/mcp. Save.

Authorize with your Onto account

Click Connect. You'll be redirected to sign in with your Onto account and approve access, then bounced back to Claude — now connected.

Use it

Onto's tools are now available. Try: "Use Onto to read https://stripe.com/pricing and summarize the tiers."

Connect in ChatGPT

ChatGPT connects to remote MCP servers through its custom-connector / developer-mode surface (availability depends on your ChatGPT plan).

Open Connectors

In ChatGPT: Settings → Connectors → add a connector (enable developer mode if prompted).

Add the Onto server

Set the MCP server URL to https://api.buildonto.dev/mcp and choose OAuth when asked how to authenticate.

Authorize and use

Sign in with your Onto account to authorize. Once connected, ChatGPT can call Onto to fetch clean Markdown and trust scores for any URL in the conversation.

Any other MCP client

Any client that supports remote MCP servers with OAuth can connect to the same URL. To test the flow end-to-end, use the official MCP Inspector:

Launch the Inspector

Run npx @modelcontextprotocol/inspector — it opens a local web UI.

Connect

Set Transport to Streamable HTTP, the URL to https://api.buildonto.dev/mcp, and click Connect to run the OAuth flow.

List and call tools

List tools, then call read_url with { "url": "https://stripe.com/pricing" }.

How auth works

The connector follows the MCP authorization spec: the client discovers Onto's authorization server, runs a standard OAuth 2.1 flow (with dynamic client registration and PKCE), and you sign in with your existing Onto account. Onto issues the client a scoped token — there's no long-lived API key sitting in a config file.

Tool calls are attributed to your account and count against the same monthly quota and credit balance as the Read API and the local MCP server. Manage your plan at app.buildonto.dev/read/billing.

Remote connector vs local server

	Remote connector	Local server (@ontosdk/mcp)
Transport	Hosted — Streamable HTTP	Local — stdio via npx
Auth	OAuth (sign in with Onto account)	ONTO_API_KEY in env
Best for	ChatGPT, Claude, hosted MCP clients	Claude Code, Cursor, Cline, Zed, local IDEs
Setup	Paste one URL, authorize	One mcpServers config block + restart
Tools	Same six tools	Same six tools
Billing	Your Onto plan + quota	Your Onto plan + quota

Same engine, same tools, same billing — pick the connector for chat surfaces that speak OAuth, and the local server for IDEs where an env var is simplest.