Connectors (MCP)

What connectors are

A connector is a Model Context Protocol (MCP) server: a program or online service that offers tools in a standard way. Asyncat connects to it and offers its tools to the agent next to the built-in ones, named mcp__<connector>__<tool>.

Manage them in Settings → Connections → Connectors. Press Add connector and choose how to add it: Catalog, Remote server or Program on this computer. Keys and sign-ins are saved encrypted on this computer.

The catalog

Well-known connectors you can add in one step:

Signing in opens the service's page in your own browser, and it sends you back to Asyncat when you're done.

Add any connector

Any MCP server works, not just the ones in the catalog.

Remote server

• Address: the service's MCP address, often ending in /mcp. Its own docs give it.
• Connection: Streamable HTTP for current servers, or SSE for older ones.
• Sign in with OAuth when the service offers it, or give a key under Headers, one per line, such as Authorization: Bearer your-key. You can also set an OAuth client ID, client secret and scopes.

Program on this computer

• Command: the program and its arguments, as you'd type them in a terminal, such as npx -y @modelcontextprotocol/server-everything.
• Environment variables: KEY=value, one per line. API keys go here and are saved encrypted.
• Working folder: where it starts. Leave it empty for your home folder.

A program connector gets the keys saved for it. Asyncat's own keys and tokens are never passed on. It runs as a program on your computer, outside the command sandbox, so add ones you trust.

Downloads ask first

Some commands download the connector before they start it: npx, uvx and docker, for example. Asyncat shows what will be fetched, from where and how big it is, and nothing downloads until you press Download and start. You can also Add, but don't download yet.

Your OK covers the version that was shown. Once an npx package is on this computer, it starts from there without going online.

Which tools ask

Each connector says what its tools do. A tool that says it only reads runs without asking. Every other tool asks first with the usual approval card, and so does a tool that says nothing about itself. In Plan mode, only the read-only ones run.

What a connector returns is marked as outside information, not instructions. See Privacy & safety.

Limit agents and Cats

Each agent and each Cat can be limited to the connectors it needs:

• All connectors, including ones you add later;
• Only the ones I pick, and nothing else, even ones you add later;
• for a Cat, the same connectors as the agent it uses as its brain.

Set it in the agent's editor (Customize → Agents) or under a Cat's Brain. See Agents and Cats.

data/mcp.json

Connectors are saved in mcp.json in Asyncat's data folder, in the format other MCP apps use, so a config copied from elsewhere works as it is. Changes apply without a restart, whether you make them in the app or in the file; only connectors whose settings changed reconnect.

{
  "mcpServers": {
    "git": {
      "command": "uvx",
      "args": ["mcp-server-git"]
    },
    "linear": {
      "url": "https://mcp.linear.app/mcp",
      "type": "http"
    }
  }
}

• A program has command, args, and optionally env and cwd.
• A remote server has url, type ("http" or "sse"), and optionally headers and oauth.
• "disabled": true keeps a connector without starting it.
• Keys and tokens in the file (environment values, headers, an OAuth client secret) are encrypted, including ones you type into the file by hand, so the file on its own gives nothing away.

If the file isn't valid JSON, Settings says so. Fix or remove it to manage connectors in the app again.