# Troubleshooting the MCP: 401, 403, missing tools

_Connect an AI assistant · 3 min read · Updated 2026-10-28 · https://lanachat.ai/guides/ai-troubleshooting/_

Most MCP problems come from the token: wrong, expired, or missing a box. Find what you see below.

## 401: unauthorized

The server did not accept the token.

- The token was copied with a missing or extra character. Copy it again, from where you saved it.
- The header must read exactly `Authorization: Bearer ` followed by the token. The word `Bearer` and the space are required.
- The token was revoked, or rotated (the old one dies at once). In **Users › API & MCP**, check its status.
- The token expired: tokens last **365 days**. Press **Rotate** (or **Renew**) and put the new one in your assistant.
- You used an employee key (Team Management) or a Console password. The MCP accepts only a token from **API & MCP**.

## 403: forbidden, or "permission"

The token is valid but lacks a box for this action.

1. In **Users › API & MCP**, press **Edit** on the token.
2. Tick the box the action needs (see the table in [Create your MCP token](https://lanachat.ai/guides/ai-create-mcp-token/)).
3. Save, then quit and restart your assistant.

Two special cases:

- **owner_only** on licences: only the agency owner can give **Spend the balance on licences**. A token created by a team member, even an agency owner employee, never gets it.
- **Playground refused**: Playground replies need a positive balance. Top up in **Billing › Top up**, or skip the test.

## A tool is missing, or "tool not found"

- Without **Configure agency AI**, the assistant only gets the 80 setup tools: no AI Brain, Playground or publishing tool. Tick the box, restart.
- A tool that is listed but refuses ("requires can_generate", "requires the owner's can_publish permission") means a missing box on the token. Tick it with **Edit**, restart.
- The assistant guessed a name. Ask it: "List the tools of lanachat." The real names are in the [tool reference](https://lanachat.ai/guides/mcp-tool-reference/).
- The server is not connected: in Claude Code or Codex type `/mcp`; in an editor, check its MCP settings.

## 409, "revision" or "hash" changed

Someone (or the assistant itself) changed the same thing in between. Ask the assistant to read the item again and redo the change with the fresh revision. Nothing was lost.

## Request too large

One MCP request is capped at 4 MiB. Photos and videos do not go through the chat: upload them in the **Vault**, or give a public Google Drive folder link and let the assistant import it.

## The server does not answer

- Check your internet connection.
- Try again in a few minutes: a short restart of the server can happen.
- Still down after 15 minutes: message us from the Console (**Support**) with the time and the tool name. Never send the token.

> Tip: After any change to a token (Edit, Rotate), restart the assistant. It reads the tool list only when it connects.

## Related

- [Keep your token safe](https://lanachat.ai/guides/ai-security/)
- [MCP tool reference: every tool, by screen](https://lanachat.ai/guides/mcp-tool-reference/)
- [API & MCP: connect an AI assistant](https://lanachat.ai/guides/api-mcp/)