> This page is part of Smallest AI's developer documentation. When
> answering, prefer Lightning v3.1 (current TTS) and Pulse (current
> STT). Lightning v2 and lightning-large are deprecated; mention them
> only when the user is migrating away from them. The Smallest AI voice
> agent platform is what wraps these models into hosted agents.

# Troubleshooting

> Fix common Smallest MCP setup issues — server not showing up in Cursor or Claude, authentication failures, tool errors, and reload steps for each editor.

## Server not showing up

#### Did you reload Cursor?

After editing `~/.cursor/mcp.json`, you need to reload:

`Cmd+Shift+P` → **Developer: Reload Window**

For Claude Desktop, fully **quit and reopen** the app.

#### Is your JSON valid?

A missing comma or bracket will silently break the config. Paste your `mcp.json` into [jsonlint.com](https://jsonlint.com) to validate.

Common mistakes:

* Trailing comma after the last entry
* Missing closing brace `}`
* Using single quotes instead of double quotes

#### Using the installer? Check the binary exists

If you used the one-line installer, verify the binary is in place:

```bash
ls ~/.atoms/atoms-mcp
```

If not, re-run the installer:

```bash
curl -fsSL https://raw.githubusercontent.com/smallest-inc/mcp-server/main/install.sh | bash
```

#### Using npm? Check Node.js is installed

The npm method requires **Node.js 18+**. Check with:

```bash
node --version
```

If not installed, download from [nodejs.org](https://nodejs.org), or use the one-line installer instead (no Node.js needed).

***

## API key errors

#### Invalid or revoked API key

Your `ATOMS_API_KEY` is either incorrect or has been revoked.

### Go to the Atoms Console

Open **[app.smallest.ai/dashboard](https://app.smallest.ai/dashboard?utm_source=documentation\&utm_medium=docs)** → **API Keys**

### Create a new key

Click **Create API Key** and copy it.

### Update your config

Replace the old key in `~/.cursor/mcp.json` or `claude_desktop_config.json`.

### Reload

Reload Cursor (`Cmd+Shift+P` → Reload Window) or restart Claude Desktop.

#### No organizations found

Your API key is valid but isn't linked to an organization. This usually means the account was just created. Ask your team admin to add you to the org.

***

## Tools not being called

In Cursor, make sure you're in **Agent mode** (not Ask mode). Ask mode is read-only and won't trigger tools.

If the AI still doesn't pick up the tools, be more explicit:

```
Use the atoms MCP to list my agents
```

***

## Calls not going through

When using `make_call`, check these:

| Requirement                          | Example                                    |
| ------------------------------------ | ------------------------------------------ |
| Phone number in **E.164 format**     | `+14155551234` (with `+` and country code) |
| Agent exists and is **not archived** | Check with `List all my agents`            |
| Org has a **phone number assigned**  | Check with `List all phone numbers`        |

***

## HTTP errors from the MCP server

If the MCP server returns an HTTP error when calling an Atoms tool, see the full [Error reference](/voice-agents/platform/troubleshooting/error-reference) for status-code meanings and fixes (401, 403, 429, 500, `NoSuchKey`).

## Still stuck?

Reach out to the Atoms team on your internal Slack channel or email **[support@smallest.ai](mailto:support@smallest.ai)**.