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MCP

You point Veyyon at an external program (a database bridge, a browser driver, a hosted API) and its tools show up in the session, ready for the model to call. The Model Context Protocol (MCP) is the standard that makes this work. Veyyon speaks it as a client: it connects out to MCP servers and consumes their tools and data. It is not itself an MCP server binary. To embed Veyyon in an editor, use ACP (veyyon acp); to drive it from your own process, use the SDK.

What it looks like

You register a server in an mcp.json file, and its tools become callable. A minimal local server:

{
  "mcpServers": {
    "sqlite": {
      "type": "stdio",
      "command": "node",
      "args": ["/path/to/sqlite-mcp/index.js"],
      "env": { "DB_PATH": "/var/data/app.db" }
    }
  }
}

Each tool an MCP server exposes appears namespaced as mcp__<server>_<tool> (a single underscore between server and tool, for example mcp__sqlite_query), so a server never shadows a built-in tool or another server. If you turn on discovery.importForeignConfig (off by default), Veyyon also discovers MCP entries from the user-level configs that Claude, Cursor, Codex, OpenCode, and related tools already wrote, so a server you configured elsewhere often works without re-registering it. Discovery never reads a working tree: a repository’s own mcp.json is not a server source.

For the full setup path, choosing a transport (stdio, http, sse), passing environment variables, authenticating (bearer token or OAuth), approving tools, the /mcp commands, and fixing common connection errors, see MCP server setup.

Not to be confused with

  • ACP (veyyon acp): the Agent Client Protocol for driving Veyyon from an editor. That makes Veyyon the agent an editor talks to; MCP makes Veyyon the client that talks to tool servers.
  • SDK: embedding the agent in your own host process.