MCP servers

An MCP server gives the AI that builds your apps the tools of a service you use: your notes in Notion, the issues in Linear, the errors in Sentry. It is for building, not for your apps: an app never calls it. The AI uses their tools when you ask in the editor's chat, and can read from them before it builds.

Press + at the top right of the Connectors page, then MCP server, and fill in:

• Name. Whatever you call it, like Linear.
• Server URL. The address from the service's own MCP guide, usually ending in /mcp, like https://mcp.linear.app/mcp. It has to start with https:// and be on the public internet. A server that runs on your computer as a command cannot be added.
• Authentication. Sign in (OAuth) for most hosted servers: a window opens at the service, you sign in there and allow Setherion. Bearer token for a token or API key the service gave you. None for a public server.

The server's page lists its tools, each marked Reads only or Can change data, and has Test connection and Sign in again. The servers are under MCP servers, in Added by you on the left.

Allow, Ask or Deny

Beside each tool, choose what Setherion's AI may do with it:

Every tool sets them all at once, and Back to the defaults undoes your choices.

In the chat

With an app open, ask in the chat for something one of your servers holds, like "Read the brief in my Notion and tell me what the app is missing". The AI reads which tools it needs and runs them, and each one shows as a line in the reply.

A tool on Ask stops the reply with a card that shows what it would send:

• Allow once runs it this time, and the reply goes on.
• Always allow runs it and sets it to Allow on the server's page.
• Deny stops the reply there, at no cost.

A reply that uses tools costs a chat reply, and one more each time the AI goes back to the model with what a tool returned. One reply runs six tools at most. The card shows what going on costs, and it waits ten minutes: after that, ask again. What a tool sends back is treated as information from that service, never as instructions, and the chat never changes your app's code.

When you build

A message that names one of your servers, like "Build the booking app from the brief in my Notion", stops above the message box first:

• Read from Notion reads what the build needs, like the page or the issue you mean, and the build starts from it. The button shows the price: three chat replies, whatever the reading takes.
• Build without it sends the message as it is, and nothing is read.

What was read reaches the build as a document, like one you attach: a brief with the texts, names and prices the app must show copied word for word. Tools on Ask show their card on the bar, and Deny keeps a tool out of it.

When the service is also one your apps can use, like Notion, the This needs Notion bar has Read from my Notion server as well. Use it when the build only needs what is in your Notion, and Use Notion here when the app itself should work with it.

• MCP servers are yours alone: nobody else in a team workspace can use them.
• The address, the token and the sign-in are kept encrypted on our servers, and never shown again.
• Deleting one removes it from Setherion. To revoke the access at the service too, do it in that service's own settings.
• You can have up to 20.

This is for the tools of a service. To let an AI assistant such as Claude or ChatGPT work with your Setherion apps, which is the other direction, see MCP: connect an AI assistant.