MCP Servers

Bundle Model Context Protocol servers to provide agents with additional tools and data sources.

Plugins can bundle Model Context Protocol (MCP) servers to provide the agent with additional tools and data sources.

Configuration Format

MCP servers are configured in .mcp.json at the plugin root.

{
  "mcpServers": {
    "plugin-database": {
      "command": "${PLUGIN_ROOT}/servers/db-server",
      "args": ["--config", "${PLUGIN_ROOT}/config.json"],
      "env": {
        "DB_PATH": "${PLUGIN_ROOT}/data"
      }
    },
    "plugin-api": {
      "command": "npx",
      "args": ["@company/mcp-server", "--plugin-mode"],
      "cwd": "${PLUGIN_ROOT}"
    }
  }
}

Server Configuration Schema

Field	Required	Type	Description
`command`	Yes	string	The executable to run. Supports `${PLUGIN_ROOT}`.
`args`	No	string[]	Command-line arguments. `${PLUGIN_ROOT}` is expanded.
`env`	No	object	Environment variables. Values support `${PLUGIN_ROOT}`.
`cwd`	No	string	Working directory. Supports `${PLUGIN_ROOT}`.

Lifecycle

MCP servers MUST start automatically when the plugin is enabled.
MCP servers MUST stop when the plugin is disabled or the session ends.
If a server fails to start, the tool SHOULD log the error and continue.

Discovery

Tools MUST discover MCP server configurations in:

.mcp.json at the plugin root
Inline in the manifest's mcpServers field
Any additional paths declared in the manifest

Compatibility

This spec does not redefine the MCP protocol. Plugin MCP servers MUST implement the Model Context Protocol as specified by that project.