# Configuration

> The local server's settings, version pinning, and what its errors mean.

Source: https://docs.buildonto.dev/mcp/configuration
Section: MCP server

---

Configuration\[01\]

## Configuration

For the local server — `npx -y @ontosdk/mcp`, currently 1.5.2, on Node 20 or later. The remote connector needs none of this.

### Build your config

\[02\]

Version**@latest** newest on every launch**@1.5.2** pinned, for reproducible agents

**Skip the registry check** no lookup for a newer version on launch

API base _optional_


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

Keep the key in the `env` block, not the command line — some clients log their arguments. Without `@latest`, npx can keep reusing a copy it already downloaded.

### What it reads

\[03\]

VariableDefaultWhat it does

`ONTO_API_KEY`requiredYour `onto_sk_` key. Without it the server exits as it starts.

`ONTO_API_BASE``https://api.buildonto.dev`Where tool calls go. No trailing slash — it's joined straight onto each path.

`ONTO_NO_UPDATE_CHECK`unsetAny value skips the npm lookup for a newer version. The one-time what's-new note still shows.

It reads nothing else.

### When it goes wrong

\[04\]

You seeDo this

The tools never appearQuit the client fully, check the config is valid JSON (one trailing comma breaks it) and in the right file, then reopen.

The server exits straight awaySet `ONTO_API_KEY` in the config's `env`.

“Monthly plan quota exceeded and credit balance is empty”Out of credits for the month (402). Top up or upgrade on [Billing](https://app.buildonto.dev/billing).

“Onto API rate limit exceeded”Too many calls at once (429). Wait a moment — the local server doesn't retry for you.

A call gives up after 15 secondsThe page was too slow to answer. Try once more, then skip it.

### Limits

\[05\]

PlanCredits a monthCalls at once

Free1,0002

Starter10,0005

Growth100,00020

Scale500,00050

**Same balance as the API.** `score_url` is free; every other tool costs what its endpoint does, and `batch` costs one credit per URL. Free stops at its 1,000; paid plans can carry on with bought credits.

Copy as Markdown[](/mcp/configuration.md "Open the raw Markdown")

---
## Structured Data (JSON-LD)
```json
{
  "@context": "https://schema.org",
  "@type": "WebSite",
  "name": "Onto Docs",
  "url": "https://docs.buildonto.dev",
  "description": "How to use Onto: serve AI agents Markdown from your Next.js site, call the Read API, connect over MCP, and read the AIO score.",
  "inLanguage": "en",
  "publisher": {
    "@type": "Organization",
    "name": "Onto",
    "url": "https://buildonto.dev"
  }
}
```